Your next blade will depend on WHY you like the PM2. I love many of my knives for different reasons. If you like the smoothness of the PM2, you may be somewhat disappointed by the Military. The Military is a great blade and I have several, but it is just not as smooth as the PM2. If you like the compactness of the PM2, the ZT560 may be a bit bulky. If you like the fact that the PM2 is light, the Contego may not work for you. Basically, the PM2 is a great knife for several reasons...you might have issue with several knives for different reasons.
Having said that, the 3 blades I mentioned above are likely amongst the ones I would also recommend:
1. Military - Bigger/Older brother of the PM2
2. ZT0560/561 - I don't have one, but I want one and the ELMAX blade is something I want to try out.
3. Benchmade 810 Contego - Heavier and bulkier than the PM2, but it did manage to bump my PM2 out of my pocket. I love the toughness of M4...but don't like that fact that the blade is coated. I think I'm going to end up stripping that blade once I form my final opinion about the durability of Cerakote.
4. Endura 4 - Slick, long blade in a small, lightweight package. I have mine in ZDP189...and it's slick
5. BM 950 Rift - Compact like the PM2...in a different steel and a more durable bladeshape (tip-wise).
Welcome to the sickness...it is addicting.