For a serious game, the single stars are best. For 3v3 go with the Large Random Single Star. For 4v4 I prefer the Huge Random Single Star.
Personally, I also have a soft spot for the Large Random Multistar in 4v4 but that doesn't always result in a good game. The problem is that the worm holes and the multiple stars destroy any concept of having a "flank" or a "front line". Sometimes it's a good game, other times you end up with big fleets that run around, often refusing to fight head on.
It's too bad we can't talk about custom maps since the game won't auto-download them (for online multiplayer).
Overall, my favorite game is the Huge Random Single Star in 4v4 or 5v5.