I would say all of the above depending on my time available. But I do like huge maps.

1. If I have to choose, I'd go with randomly generated but if at all possible, both.

2. Unexplored.  You need to send units out to see what's out there.  Same as it would be in real life.

3. I'm open to new ideas.  Why not?  As long as it's an option and you can turn if off if it introduces gameplay issues I can't anticipate.

4. Huge maps.  As big as possible.  It has to feel like a war, not a confined battle. This was the biggest downfall of Supreme Commander 2.  The maps were way too small.  The sheer scale of the theater of operations is what makes the game.

1.  I will go for both if its possible. Well known maps may be more optimized with less bugs but you get tired of them, while a map Generator may create really awesome and different maps each time but how optimized and bug free is? a Good player for me will play any map given without a problem.
2. Completely unexplored. Anyway having connected regions in game (yellow lines) you cannot get lost, just follow those lines and it will take you to the next region to conquer.
3. All options are welcome to add when you setup a game, But no i will prefer when you take a region and that region get explored while the others around it stay unexplored, why you have a radar in the game if you don't put it to work?
4. I will love to use the game full Engine power, using thousands of Units at a the same time, that's one of the things that made me buy the game, so it means bigger maps are better for me, that's why you have save and load game, if your out of time then just save it and come back at a later time to finish what you started.

 :

1. Option for Random but of course some to remember and have strats for/have favorites.
2. Unexplored/Fog of War - Or toggle option
3. After I gain control of that region, FoW dissipates to reveal it.
4. 45min - 1:45  /  If possible, hours upon hours.