I'm a 29'er guy but I'm also 6'3". Some people complain about 29" wheels being hard to make tight turns and having more felt gyroscopic effect but I don't notice those as much on an XL frame. Bikes are almost as hard to get as guns and ammo now so you'll have to be the lookout. Geometries have really changed over the last few years. 'Low & Slack' are very popular (low bottom bracket height & slack headtube angles). You will be in a much more upright position than the GT frame.
I had really good luck with a Trek 120mm full suspension until recently switching to a carbon frame. Trek, Giant, Specialized, etc. are all going to be pretty good 'bang-for-the-buck' rides, it will just be your preference. I'd also consider Marin and Jamis as well. I had a back-up bike from Marin and it was a great bike at a really good price. I've seen some good deals on the Mountain bike Classified SouthEast page if you're interested in used...
Good luck and keep us up to date on your search!
I had really good luck with a Trek 120mm full suspension until recently switching to a carbon frame. Trek, Giant, Specialized, etc. are all going to be pretty good 'bang-for-the-buck' rides, it will just be your preference. I'd also consider Marin and Jamis as well. I had a back-up bike from Marin and it was a great bike at a really good price. I've seen some good deals on the Mountain bike Classified SouthEast page if you're interested in used...
Good luck and keep us up to date on your search!