Man this is a vague question.

Since you are saying "for the money" I would assume price is a consideration? My Vortech puts down a little over 400rwhp and was $3899 from Brenspeed. It definitely wins the "bang-for-the-buck" award I think. It is centrifugal though, which some people don't like. Brenspeed also sells a Paxton HO for $4995 that I think is a great deal for an HO kit. You can get a Procharger for not all that much more.
There are lots of choices out there, and pretty much all of the ones that have been around a while are good kits. There are some nice twin screws on the market: Saleen, Kenne Bell, Whipple. All of them are pushing 6k+ I believe.