About a month ago I was looking at buying an XTC 29er 2, Trek Cobia (couldn't find an X-Cal anywhere), Spec Carve Comp, and a Cannondale Trail SL1. I took my time and rode all 4 bikes and decided on the Giant XTC. It had the best geometry, parts spec and felt the best. I was able to get the XTC for 10% under MSRP which was nice too. So far I have ridden the bike about 60 miles and am very very happy with the bike. Before this bike I had a Spec 26er full suspension so this is my first 29er hardtail.
Of the bikes I rode I liked the Cannondale the least. It felt heavy and slow and wasn't much fun. The Carve was OK, but just too expensive and no one was willing to discount it from msrp. If I didn't get the XTC I would have probably bought the Cobia as I thought that fit and handled very well, I just thought the XTC was better and I was not happy with the parts spec on the Cobia.
I'd recommend the XTC of the three you listed. Good Luck!
Airborne Bicycles. NEW Goblin
Another bike to consider is an Airborne Goblin. It compares to an X-Cal at a good savings. It currently has a preferred dual air RockShox Reba fork, something you need a 2012 X-Cal to get. 2013 is solo air less tuneable fork. A 2012 Scott Scale Elite for about 1300 if you can find one is also a great bike with the dual air Reba and superior geo.