I voted Forgotten Realms, mainly because they staggered the release of the core manuals and used FR for the adventures that have been released so far.
Otherwise I'd probably lean towards either just using my own world, or Dark Sun because it was my favorite setting in 2ed because of its uniqueness.
The changes are interesting. I like playing my paladin and being able to be neutral good while doing it. If anything I don't think any of the oaths truly represent an evil paladin. So at least to me while there's no alignment restriction, it still feels like there is.