I believe there was already a thread about this...
Well, I'd vote for Sup Com, I've simply loved this game so far. Now I just need to get a computer that runs in more than 0.1 FPS for maps that supports more than 2 players... this game punishes me so much... I agree that they were a bit uninventive with the factions in general, but the difference is in the details, and they're a hell of a difference. Still, the beauty is in the real strategy, something hard to find in RTS, who are all about tactic (there's quite a difference).
About C&C. Well, it is entertaining, because it is C&C, but... it is also still C&C mostly. They were too conservative in the game. And Starcraft 2 is a dejá vù of that happening again, but worse. Still, it is really fun to watch "commented" games, that idea was brilliant! But the action is so fast the commenter usually get lost... Sup Com would have taken much more benefit from it. Also I noticed that they increased the pace. A LOT. It is both bad and good. The multiplayer games are basically rushes, all the time. And it is almost impossible to hold these... I'm sick of the damn scorpion rushes. I barely have my defenses deployed, or get the advanced tech building, when 40 or so scorpion knocks the front door. Sometimes I get to make a mammoth or two, but that only means that is because they're going to knock the BACK door with 40 or so stealth tanks...
--Signal Incoming--
"If I like you, you can call me Sarge.
But, guess what, I DON'T LIKE YOU! Do you understand, scumbag?
It's Sergeant General to you"