If it's for track use, I hear Tein Super Streets are too soft. They're meant to be comfortable for the street. They also don't have as much adjustment as other coilovers.
I've got BC inverted coilovers which I'm happy with for street use. Spewing I've still not been able to take them to the track but once I do I'll let you know how they go. Have a feeling they should do pretty well though. If you wanna spend a bit more the BC external reservoir coilovers are supposedly not bad.
I've not tried KW but everyone says they're awesome so they probably are. Just a bit more expensive I guess.
Do Bilstein or Penske make anything for MR2s? They're meant to be awesome if you can afford them. How much are you looking to spend?