The Spec. Enduros are more freeride bikes with some XC mixed in. The FSRxc and Trek Fuel are more XC and XC race bikes. Your riding style should help you decide which bike to go for.
Freeride bikes generally have more suspension travel - 4" front and rear minimum - beefier frames and components. Of course, they are heavier, so climbing is more difficult and XC racing is really out of the question. Jumping and descending are freeride activities with an emphasis on gravity assisted locomotion. Even so, they are not downhill machines, as DH is another specialty, but a FR bike will descend better than an XC bike.
XC full suspension usually runs 2 to 4" rear and 3 to 4" in the front. Weight is an issue as most XC riders climb as much as they descend. XC bikes are more nimble on technical singletrack, because of frame geometry and lighter weight. Overall, they are faster than a freeride bike, but are not as durable and will not handle big hits as well.
Mid-range XC bikes are raceable in the beginner and into the sport catagories, but the weight penalty (between the mid and high-end bikes) begins to show up in the sport class. A mid-range full-sus XC bike will come in at around 27 to 29 lbs., but a high-end bike will be 24 to 26 lbs.
Specialized FSR: Good all around suspension, maybe the best out there. Supple on small bumps, but be sure you get one with a rear lock-out if you do a lot of climbing. Successful on the race circuit. You may have to put up with some Specialized house-brand parts, though.
Trek Fuel: Short travel rear and less small bump sensitivity. Will ride closer to a hardtail. Light and a good value. A better race bike than general trail bike. Easy to find.
Giant NRS: (disclosure, I ride an NRS) Suspension design eliminates bobbing when pedaling - no need for rear lockout. 3.75" of rear travel is plenty for XC. Not too sensitive on small bumps since your pedaling locks out suspension. However, climbs like a hardtail. Good descender. Successful XC racer. Very good component specification and value.
So as not to offend anyone, these are just a few of the good XC bikes out there. C'dale, Intense, Santa Cruz, among others make outstanding bikes.