Some info here sucks.
First off, Giant makes frames for almost every company out there with a bike under 1k, and a ton over 1k. Dont worry about brand. Most come out of the same 4 factories in China anyways.
The Yukon is not a bad bike, in fact it won Mountain Bike Action under 800 bike shoot out a couple months back.
Anywho, first: MTBR.com/forum
Second, decide what type of riding you will do, and eliminate everything else. If you arent free-riding or jumping then the Shred should be out.
For general trail riding get a trail/XC bike. Dont get a free-ride bike, or downhill bike, and especially not a jump bike. They have very short top tubes, and are uncomfortable for general riding.
Third, get fitted/get the right size. This isnt based on standover, or handlebar height (WTF). It has to do with top tube length, it is how stretched your torso is.
Im 5'10'' and ride a 23.25-23.5 for XC riding...
and lastly, unless you find a close out or sale, generally speaking most bikes in a given price range will have very similar specs. The things to worry about are derailleurs, forks, and cranks (if your a big guy).
At 500 bucks you wont be running into any FOX anything, so ignore that...
Frankly, your will be getting a medicore fork. It may have a good name, but its crap. Thankfully, most "crap" now is still pretty decent, and with average use will take you a year or so to outgrow. By then, you will know if you want to upgrade. My fork alone is twice that...
Lastly, one of my bikes:
Brodie Nemesis
Fox Talus 36 RC2
Sram/Truvativ/Avid/easton/TBC build, albeit without front brake in this pic. 8" rotor now.