Personally, I love driving with the P2. It is pretty deep, and I realize some people don't like that, but I love it. I have one fresh one that's overstable, one very beat up star one that holds any line I give it and flies straight as an arrow out to about 270' (if I throw it any farther than that, it begins to drift right ever so slightly), and a very beat up P-line that will always turn over very slowly for the entire flight.
If deep putters aren't your thing, though, I would suggest the Gateway Shaman. I've thrown quite a few shallow putters (Zone, Pure, Chief, Wedge, XD, Dart, Ringer, etc.), and I believe that the Shaman is the most versatile. I expected it to be understable, but after a few throws, I realized that it wasn't understable, just neutral. It would turn if I wanted it to, but with a smooth release it would simply hold the line I gave it until it hit the ground.
Also, one of the things that I have noticed in my experience is that a good follow-through will make driving putters much easier. In one of Paul McBeth's field work videos, he throws a very beat up DX Roc with a hyzer, and because of his follow through, the disc maintains that hyzer angle despite its understability. This also applies to putters.