The road to 60 buff doesn't only last until one class hits 60. I'm on a preferred world and have passed 60 on 2 classes, and when I swap to any other class, the road to 60 buff comes back, so it's definitely worth going to a preferred world imo.

But yeah, since party finder and duty finder pull people from the whole datacenter, I'd say it probably doesn't really matter which world you choose, especially if you are more of a solo player.