For a one-nighter, pull through because they're usually long and level enough that we can stay hitched. Also pull-through if arriving very late at night so we create minimal disturbance. Beyond that it doesn't matter, there are dozens of other criteria for a preferable campsite more important than pull through or back in.
However, I do prefer angled back-in sites. I've been in a few campgrounds (forest service, mostly) where the sites are at 90 degrees and really narrow road with trees either side doesn't let you back in a decently sized trailer.
