first off, war3 copies starcrafts story in nearly every way possible.
Main character falls to baddies... check
Main character becomes leader of the baddies... check
Game ends with baddies winning... check
anyways.. on to gameplay
war3 relies on creeping as your sortof 3rd economy tidbit, aside from gold and lumber. Also relying on hotkeys and speed. Most people dont like this as items and hero Lvl'ing are involved which brings down skill factor I suppose (at least thats the excuse Ive heard for people hating war3). Another complaint I hear about war3 is that people dont like how the micromanagement has more than tripled when compared to starcraft.
Starcraft just requires good knowledge of unit types and weaknesses, a fast hand for those hotkeys. Also maybe a bit of micromanagement, and you're set heh. People mostly prefer starcraft as no hero Lvling or item aquiring is involved, making the game more even for those who enjoy/dont enjoy rushing.
as for my opinion, I love em both 😛 I cant help it cuz both are a blast to play. star and war3 pwnz~