I have been on a bit of a Manix spree lately, but I have to choose the PM2. Any PM2 with a stainless steel blade.
I have a lot of faith in the compression type locks like the PM2 or Manix BBL, but the PM2 fits my hand slightly better, and I like the acute point.
3.5 inch is a good sized blade for EDC
Good light weigth
G10 and liners for strength.
Open back for easy cleaning.
Effortless to open and close.
Between the 3 that I own, I'd go with the blue M390. It sharpens easier than the 20CP but holds an edge noticeably better than S30V. The 204p is still new and unused so I cannot comment yet.