I'm fency about the V6/V8 thing. The full-time 4WD and the timing belt pulls me away from the V8 a bit. At the same time, I can't see a V6 pulling the same weight getting much better mpg. Are they both pretty equivalent?
Like any 4th gen owners will tell you, you can't go wrong with either engine. I know that V8 owners love their V8's. There are many satisfied V6 owners and then there are some that regret not getting the 8. I would have probably found myself in that latter boat, had I not purchased one from the jump.
The fulltime 4WD thing, I thought might be an issue, but I absolutely love it now. The design and function of the drive-train and diffs perform amazingly. It's not like the older fulltime 4WD SUV's that were notoriously hard on tires. I find that my tires wear evenly, even without regular rotations and I get what you would expect, if not better, life expectancy from tires. It's a great feeling having sure traction on tap at all times. I find myself in awe all the time when I pull away from an uphill stop on a wet road and never break traction which would surely happen in any other vehicle. Also, I never have to mess with switching around in and out of 4WD when I'm driving and head into snow or whatever. Honesty the only downside that I've seen is that if you feel like horsing around and breaking traction to show your ass, light the tires, do some donuts, or some mess like that, then you have to re-think your approach.
The timing belt thing? Yeah, I'll agree, I'm not a fan of it. Especially considering that it's an interference engine. So it's definitely something to consider. A costly piece of preventative maintenance due every 90K miles. I don't mind having it done for that little piece of mind though.
The fuel mileage thing? When you're in this class of vehicle, you're gonna have to concede that they're not gonna be great on fuel economy. I always felt that mine was decent in stock form for what it was. A hefty SUV, with a V8 and full time 4WD. Now? Not so much. I think that the data has shown that there isn't really a huge difference in MPG between the 2 engines. Not enough for me to care anyway. You're right, both pulling the same big un-aerodynamic truck body.
Both equivalent engines I'd agree. I'm just a sucker for the torque and smoothness of the 8 cylinder. I'm pulling these big ass tires with stock gears and I don't feel like I'm hurting for any power or torque. I've driven 1GR trucks (4R, FJC, Taco) since owning mine. I know I made the right decision for me. But like everyone has said. Drive both and make the right decision for yourself. If you have no interest in an 8, then just get a 6.
Good luck on your search. Hope you get a good one!