Before the F-150, I had a Silverado 1500 w/a 350...motor went to sh!t and had to replace at 150,000...the F-150 w/a 5.4 litre has 240,000, uses some oil (about a qt between changes), but otherwise runs great...I'd run it back down to Franco's inna heartbeat...
My bet is the next post will be a guy who can swap Ford for Chevy w/the same story...it's a crap-shoot either way...you might wanna buy a 3 yr warranty for whatever you get...
As far as 2WD, I've pulled several 24'ers out w/my 2WD...but it's been on good ramps and not overly steep or slick...so that's gonna depend on what kinda ramps you have to deal with on a regular basis...you'll definately save $$ on initial purchase and fuel costs w/2WD...
I honestly don't believe anybody can predict a Ford or a Chevy is gonna last longer than the other...