It depends what you want it for. A second vote for the GF 29ers here. At TwentyFour12 last week the winning team were XCracer.com GF 29ers who all rode 29ers, more powerfully second place was a team of "just" me and my mates from our regular Brighton Tuesday night ride and 3 of us were on GF 29ers too. 3rd were the Trek 69er collective, riding GF 29er drived 69ers (of coursem had they had 2 big wheels they may have knocked us, Morvélo, off 2nd spot on the podium!). A pretty damn good demonstration of 29er speed.
Yes, it was an endurance event but the even is renowned for having one of the more technical courses and 29ers didn't feature so prominently in the Mayhem results where the course was less technical and possibly just crazy light bikes would have been a bigger advantage.
We all use our 29ers for Tuesday night singletrack thrashing, not just for race day only too.
If you've got the cash the Gary Fisher Paragon is a great super fast bike straight out the box. The XCal is great value too - same frame, fork and riding position package for a load less cash., and a great platform for upgrading if you want it to double as a race day rocket too.