x-com is for the most part a turn based rpg

Aren't we all? 

The 'best' I can think of are all old now and graphically inferior.  These include all the Infinity Engine games that were mentioned in the thread, as well as Fallout 1 and 2.

The next closest thing to a pure turn-based RPG would be Neverwinter Nights, which when playing the single player 'official campaign' game and some player-created addon modules, you can just press the space bar to toggle pause.  In practice, it's not very far from turn-based, especially considering that while it looks like it's happening in 'real-time' the combat in game is calculated by turns.

yottaFLOPs?  psshaw.  I'm waiting for lottaFLOPs.  Because you can't get more than a lotta FLOPs.  *guffaw*

Kings Bounty is good. Low key humor, sometimes high key humor, much humor at your expense! First tip, Easy Mode until you get your feet under you. This game will hand you something dear to you so quick it is hard to believe. Second tip, get one point in Scouting right away no matter what class you play. Hovering your mouse over a potential attack group (they will aggro and come after you in the overworld) will tell you whether it is too strong for you at present.

The overworld you can ride around freely on your horse. When you enter combat you go to variously decorated battle arenas and maneuver your troops and cast spells, use scrolls, stuff like that. Undocumented tricks like always move your archers one square before attacking or the archers don't do much.

Have to chuckle at a game where your first tutorial (required) is to rescue a dummy princess from an all too real and very in your face Dragon. Having survived that, your trainer treats you to a nice Necromancer! Ugh! Then a pleasant cave quest and you go out to meet the king and get rolling in the real game world. Graphics great, and seems stable at present patch level, be careful which patch you get.

What I didn't like: 1) Once a map is cleared for your current game, it doesn't respawn. 2) If not on Easy, it is possible to run out of available troops to buy. 3) You do need an army composed of various types, some usually get killed if the opposing troop is near your level, and then you must go to various vendors in the overworld to get more, sort of tedious after a while. 4) Your hero, no matter what class, is never seen on the battle field. You do participate, cast spells, summon Rage Spirits, you are there in effect, but it is a lot like being a wizard in a remote tower. Your warrior will never get to use his sword. The sword's attributes boost your other army units. 5) Whole thing sort of got old and repetitious for me by level 12, which is probably my fault rather than a defect with the game.

Planescape Torment in particular (infinity space-bar-to-pause engine).  It takes a bit of time to get going but has the best writing of any computer or video game made to date.

Another to try if you can find it real cheap ...

(Let me first move myself behind this thick flame proof shield)

... is Warlord IV Heroes of Etheria. Turn based all the way.

(I know that even now a moderator is reporting me to Brad as a dangerous lunatic!)

When Warlords IV first came out, it had a hideous memory leak and numerous other problems besides. Now, finally, five years after release the publisher Infinite Interactive in AU has gotten the money to fix their old game. Patch 1.05 has fixed the problems far as I can tell and added some new stuff like fog of war and a high level hero, Galadriel, for the campaign. Galadriel's castle is Goldshire. (heh heh) KGB has a patch 1.05a with further improvements and is at work on an even newer patch with lots of great stuff. Patch links available at Warlorders.com.

Galadriel's party members level up with incredible speed, which is helpful against the maniacal AI which is not the sharpest tool in the shed. Your 3 member retinue is persistent and they and your hero level up ever so often. Combat takes place in arenas and is automated. All you do is select a party member to go out and combat with whatever the AI sends out. Bit of tactics involved, bit of chance too since some things can lure out your weakest party member, or assassinate heroes, or do damage to the party as a whole. Towers shoot arrows, and archers in the party get a shot when each new combat starts. Siege engines blast away at towers. Pretty simple. If it is obvious you will win, just tap spacebar, instant resolve.

The campaign is not all that long, but with the optional areas pretty good size, and worth doing once. Then there are some new supplied quest maps to go with the old maps, and the random map generator, and a very easy to use map editor. The maps are quite large, by the way. Exploration is one of the things you do a lot of, capturing cities along the way, exploring ruins where you might find neat stuff, the usual. There is one quest with four parts on each map, bit challenging to complete sometimes, because the maps are quite large.

I persist in playing a bit of W4 HoE from time to time because it is such a fast game for a turn based game with so much going on every turn. Gameplay is not just your retinue group. You will have a number of parties who each turn will be up to something different.

The graphics appeal to me, your mileage may vary. There are 10 playable races. Galadriel is an Elf, but the optional areas will eventually give her the ability to lead any of the races including demons and undead, though only in the campaign and its optional maps. So you can try 'em all. Warlords 5 is planned, but no estimated release date yet.

Disciples II. You can get this combined with Rise of the Elves in the value software, jewel case section of stores at the present time for $10 or much less if they have a two-fer. I like it a lot when it first came out, except for Rise of the Elves which never appealed to me all that much. The Elves were such a bunch of dimwitted kill-crazed schmucks. As patch level 1.04 game balance seems to me to have gone down the tubes. You spend way too much time trudging back across the map to a city to resurrect party members and heal them. Taking down major groups, you really need to be a mage. Cast two spells on the enemy, assuming you have the mana. Have a thief poison the enemy party. Then attack. I notice the user community on this one is about zero. But it is a turn based classic, no doubt about it.

Age of Wonders Shadow Magic, and its predecessor. I've only played AoW:SM and it is more than impressive. Very nice graphics, you can zoom in too! Turn based across an overworld, and there is an underworld too. Combat in large arenas and you may move your troops around for optimum tactical advantage. Or just press auto combat and sit back and watch, the AI is quite good, usually better than me. AoW has an active player community at present. Very active really.

16 or 17 playable races. Good campaigns, etc. But here is the really impressive part.

The community has produced a super patch, version 1.4, that adds simply an awesome amount to the game. Awesome. Even more awesome, they are at work on patch 1.5. But there are also mods, additional maps, etc. The game may be 5 years old, but it is a very active and alive game at the present time.

http://www.triumphstudios.com/shadowmagic/communityupdate.php has the links to the super patch.

http://aow.heavengames.com/cgi-bin/forums/display.cgi?action=t&fn=29

And above is the link to the General Discussion of the active forum for AoW: SM.

(I'm not sure these are classified as RPG in any sense, but they are turn based.)

In the Infinity games, combat and movement were resolved according to rounds, though by default the start and end of a round (turn) passed without user-interaction to provide for an (almost) real-time effect.  However, there were non-default options that could be set to stop the game at the end of each turn (or according to any or all of about 6 or 8 other conditions).

Aurora (NWN) combat was calculated and resolved on a per-turn basis.  And the game could be paused manually (default: spacebar key functionality).  But unlike the feature in the Infinity Engine you couldn't set it to stop at the end of a turn, though it could probably be scripted (modded) to do so.

I don't know Odyssey or Electron features well-enough to comment on that.

I strongly recommend the original Neverwinter Nights for RPG gaming... thousands upon thousands of new realms created by gamers available for free download.

If I ever find time I'll check out Kings Bounty which several mentioned was a good TBS.

Arcanum, as has already been mentioned.

If you like minimalist (read zero) graphics, roguelikes are worth trying. Ancient Domains Of Mystery is great. Just don't expect to win and don't look at it if you think your character should look better than an @ sign.

If you include non-isometric Turn Based RPG's, the Might and Magic series is fantastic. I recommend starting with World of Xeen (combined install of M&M 4 and 5 leads to an actual blend of both games) - then progressing backwards to #3 and before.

"Come here; I'll make ya a dead guy!"

"Ararahahrgh!"

Birthright, to me, was always the game that just could've been so incredibly awesome, but juuuuust missed.  (Of course, I've still spent many, many hours playing it over the past years.)

There are so many neat, interlocking little pieces, but so many of them just don't really do anything meaningful (like contesting non-Law-related guilds).

I also didn't like how your regent never really managed to get enough XP to go up to high levels, so that starting as a Wizard 12 regent gave you access to a lot of cool options that would never be available in even a long game when you started with a Wizard 3 regent.

Also, you couldn't play for total global domination, because you always won the game before you could conquer the world.

I may need to go reinstall this ...

http://www.spiderwebsoftware.com/geneforge4/index.html

I wasn't to hot for his Avernum series, but Geneforge 4 was a great game. Looking forward to his release of Geneforge 5.