sertguy
Observer
I think the 2008 and 2009 are the best options. In general they are all mostly reliable, so low mileage and good condition win out over various years and configurations. However...
Earlier ones, 2005 to 2007, have more widespread frame rust issues and a known weakness in the engine mount brackets that was beefed up in later frames. That frame reinforcement was a running production improvement in model year 2007. From 2008 to 2015 the frame was unchanged. There is a fair to high chance a 2005 to 2007 will have a new frame under the service campaign. In that case the frame will be new and of current production, so that moots the point. My truck is included in the frame replacement campaign but wasn't rusty and wasn't eligible for replacement.
Toyota changed the piston design in 2012 in the 4.0L V6 that had led to more piston slap, so the 2012 to 2015 engines are just now getting enough miles to see if this will be a long term issue. These trucks also have an air pump in the emissions systems that earlier trucks do not (at least my 2008 does not). This pump is just kind of a headache it sounds like.
The 2009 and later have A-TRAC, VSC, LSD and integrated back up cameras. More electronic junk to eventually fail. The trucks with VSC have a complex electronic brake booster/anti-lock master cylinder. The pre-2009 non-VSC trucks have a traditional vacuum booster, the anti-lock controller is completely separate and is easy to defect just pulling the fuse. The 2005 to 2008 trucks have these systems as options still.
That's why I specifically looked for a 2008 and 2009 TRD. I got the vacuum booster M/C and electronic locker without getting most of the nanny systems. If you get a non-TRD that has a limited slip it was mechanical from 2005 to 2008. In 2009 it became an electronic LSD using the TRAC/VSC system.
FWIW, if I didn't find a TRD I would have zero issue with a plain SR5 or even SR because the only TRD-specific stuff that I still have is the locker and the 120V inverter in the bed. The inverter, meh, and the locker could easily be solved with an Air Locker or e-locker retrofit. Otherwise the TRD got me fender flares that are color matched, whatever, and some bed-side stickers (which are slated for getting removed at some point, I'm definitely NOT about the flashy). I had a laundry list of things I was looking for, V6, 6-speed stick and being TRD just meant less work installing the locker.
Did Toyota make same changes mention above to the 4runners as the Taco's in 2008 and 2009? Have the same question as the OP but for 4Runners. Thx.