V6 because I have the same engine in my Tacoma and it's been very reliable (105k on the Tacoma and I bought it with 12 miles on it), and I couldn't find a V8 4x4 while I was looking.
I would like to know just how many forum members who own a 4runner in 4wd and V8 or V6. How often do you need the 4wd?
I read many threads where when needing repair, those 4wd 4runners really cost a lot of money to get fixed.
Also there is a lot of extra weight involved with any 4wd.