Re: 2007 or 2014
I was in the same spot recently. Ended up with a 07, 52k miles for $24k. The PO appears to have always garaged it, never took it offroad, maintenance regularly at the dealer etc. The 12/13/14 years were all well into the low/mid $30k range locally; I would rather spend the difference in price on mods, and honestly, a difference of 10 or 20 k in miles on one of these rigs is negligible in a Toyota.
I looked really hard at the 8.0 vs 8.2 rear diff issue specifically. I planned all along to re-gear, so the issue became whether the 8.0 housing with substantially inferior. Two FJ specialty shops told me that they have not seen an FJ come back with broken gears where they have been replaced with good quality 4.56's running 33"s. That was the deciding factor for me. My concern was that I might be buying the equivalent of a Jeep Wrangler with a Dana 35 rear end... but that is NOT the case ... the 8.0 is pretty decent.
If I were building a hard core rock rig, I would be putting in Dana 60's anyway (with an SAS front) so all the talk about 8.0 vs 8.2 would be equally irrelevant.