I've been riding the same mountain bike since 2002. It's time for an upgrade. I worked at a bike shop from 2001- about 2007.
My current ride is a 2002 Giant XTC SE2, which was a pretty standard entry-level-race XC bike at the time. It's been upgraded heavily over the years, but in general, it's the same DNA from the day I bought it: 26x2.125 wheels, mediocre rockshox duke fork, cable disks, lightweight aluminum frame, 3x9 drive train, etc... I tried to go tubeless but they never held air right and so I am running tubes ATM. I ride all over the lower peninsula but currently my primary trails are Highland and DTE, and then Pontiac Lakes and Holdridge. I recently moved to Milford, but have yet to try out other trails in the area.
Things I like about the bike I have now:
-Light
-Climbs well on smooth
-Sprints great
Things I don't like (in order):
-Stability. I don't know if its because I have gotten older and heaver or my tires are just wrong (Hutchinson Python 2.0s), or my fork is trashed (highly likely), but lately it feels like the bike is just more squirrely and unforgiving than it used to be. I put narrower bars on it a while back, so I'm sure that is part of the problem. This is probably my main complaint.
-Geometry. I feel like I have too much weight on the front wheel at almost all times. It's next to impossible to wheelie and its tough to get my weight back appropriately on decents with drops. There have been times where I have been close to pulling a tire off a rim on a banked turn after at speed after a long decent.
-Climbing Traction. As soon as you hit those root sections on the uphill, your wheel bounces, legs spin and energy is sapped.
Stuff I want:
-I want to be able to ride DTE full out without feeling like I don't have 'enough bike' under me (berms ruts jumps hawtlapz). That being said, I'm 34 so there will be a measured amount of send.
-I want to be able to keep traction on ascents.
-I want something to be kinder to my wrists
-I dont want to feel slower than I feel now (if possible).
Bikes I am considering:
-Stumpjumper
-Trek Stash
-Trek Fuel
-Giant Trance
Other Factors
-I will likely want to keep the existing bike and try and update it to fill a niche
-I will likely be riding the Milford trail, Proud and Island Lakes more
-I know I'm old and fatter than I used to be