D&D 3.5e, at least for the moment. Hopefully, that will change when I get a chance to read, digest, and (most importantly) play 5e.
(Of the three you list, it's Pathfinder, simply because it's the closest. But my opinion of that game has always been that while it's better than 3.5e, it's not better enough to persuade me to abandon my years of system mastery to get the upgrade.)