I have yet to see a valid argument for StarCraft over TA. Most of you who prefer SC over TA simply state that SC is more popular than TA. That does not mean that it is a better game technically. I will agree that SC has a better story than TA, but thats about it. Total Annihilation uses fully rendered 3D units as well as a realistic physics system. StarCraft is stricky 2D with no physics at all, granted that SC does have some nice looking artwork, but thats to be expected from Blizzard. Secondly, the AI for TA is far better, now I'm not talking about an AI player that you would play in a skirmish battle, I'm talking about the units individual pathfinding and responses when left to their own devices. StarCraft's AI is so "dumb" or bad that most games are won by exploiting AI behavior, so it really matters not wich game has more units or playable races. Finally, if you say that SC is better because of custom maps and game scenarios chances are you have never played TA or have played it very little. TA has all the same custumization and more. How about new units,and a MOD community that leave StarCraft found wanting.
Look, in the end I'm not saying that SC is a bad game, I enjoy a good game of SC from time to time. But the two games are really like comparing apples to oranges the only thing they have in common is the RTS genre'.