4wd is actually a misnomer. It's not 4wd it's really 2wd, one in the front and one in the back unless you have limited slip in both pigs (which is rare) most are rear only, the front pig is open spool.
If you have limited slip in back, then it's 3 wheel drive.
I have lockers front and back so I'm true 4wd bit that is rare today and it's aftermarket.
Resale value on a '4wd' is always better but then the maintenance is higher too and conversely, load carrying capacity drops with a 4wd versus a 2wd. Most people never take that into consideration.