I use either, always depending on the mood of the moment, otherwise known as whatever sounds best for what I'm working on. It's wonderful having the two different filters. My first P5 was a rev 2, but in those days, I was recording to 4-track cassette. My wife has a rev 3, which I used for a couple years until the rev 4 came out. There's no way for me to compare my teenage rev 2 and the rev 3 I now have access to.
I have placed the rev 3 and rev 4 side by side, in true synth geek fashion, and while the differences are interesting, they're both Prophet 5s and sound as such!