IMO, Starcraft 1 is better than both 2 and 3.

III has a better and more interesting story telling. But gameplay wise I really like the starcraft 1 system without the heros. I think warcraft 3 adds too much complexity and gimmickry that takes away from fun RTS gameplay.

That said, Warcraft 3 mods were the shit. There were so many fun and inventive modes of play that you could just barely do with starcraft and not at all with warcraft.