Congrats on the 4runner purchase! Either one would have been a great choice ! I've been in both, own a 4g v8 and prefer it, but it's all what feels good in the end and what fits your needs!
I've owned a few 4Runners and the sixes always seemed to eat head gaskets due to the power/weight ratio. I went through the same dilema but it came down to the 4.7s history with the Land Cruiser. Toyota has the best Perown Cert on the market so with those miles it should be a non issue. Let someone else take the depreciation hit.