If it was me, I'd get a 2007 Tundra Crewmax with SR5 and TRD packages, because the 2007's are the best
The truck may be getting a new look, exterior, interior, and motors for 2014. I think if you get into a newer truck (2010 or so), that you'll lose more equity quicker, when the redesigned Tundra comes out. If you get a 2007/2008, you are getting one of the first years of this model, and you'll probably lose less in value.
The differences between 2007 and a 2010 is that, after 2009 (I think), the "packages" changed, and you had to spend more for less (i.e., buy more packages/spend more money to get the same features as a 2007-2009 truck came with for a lower cost).. .something like that. Also, the tail lights are different on the 2010+ trucks, and so is the front grill. Both of those things can be changed/upgraded on a 2007-2009 truck for a few hundred dollars. Easy to change out, and really a minor change. Aside from that, almost everything is identical, except again, some of the interior creature comforts were deleted on 2010+ trucks, that the 2007-2009 trucks have
There may be some other minor differences that I don't know about, or forgot, but none of them are important enough to take into consideration, especially when you are comparing a used truck that may cost you high teens, to a used truck that will cost you mid to high twenties. If you can find a good condition, decent/low mileage 2007/2008 at a great price, that would be a win, IMO.
Also, if you have any plans of lifting or leveling the truck, stay away from 2010+ Tundras. Something changed in the manufacturing process of the steering racks, and those guys are blowing them left and right. (not everyone, but a lot of them). I have yet to hear of a 2007-2009 Tundra with a blown rack, and if there are some out there, it isn't as widespread as the 2010+ trucks.