In my expericance AOE games last about 3-4 hours (depending on a lot of factors) where C&C almost never last more than I got ur CSS joke before I read it was from CSS.

If your looking more for a 'lets build a massive empire and end them all in one fell swoop' I would definatly go with AOE. If your looking for a quick distraction, fast action, and deaths that look like melting tomatos then I would go with C&C. It depends on what you feel like playing i guess. AOE in my opinion is the number one greatest RTS of all time, C&C would probably be second. With how Dawn of war 2 is looking- it could be better than Starcraft 2 potentially, if Relic.

The more interesting confrontation would be Starcraft 2 versus Dawn of War 2- that'd be a more interesting face off I think. The original Red Alert was awesome, but after EA consumed Westwoods soul, none of the C&C games have been very good. Of course the two games are difficult to compare since they are so vastly different. Starcraft 2 would probably butcher Red Alert 3. (Espiecially since it was used in Star Wars: Galactic Battlegrounds ) AOE is much more complex, with more units, more buildings, better chances to expand your base (always hated 'sandbagging' for second bases in C&C), more resources, and I think the engine is built better. I prefer it over C&C for a few different reasons. Age of Empires 2 has always seemed to me to be about the best game in the world.

Starcraft vs command and conquer