I've heard that SOG doesn't currently have either pistol. A bunch of Bulgarian Makarovs are supposed to become available in a month or two, and probably more PA-63s as well. I have two of each and like them all. The PA-63s are more like Walther PPs in design. They hold one less round (7+1 vs. 8+1 for the Makarov). The PA-63 is a little lighter and thinner, has an aluminum frame, a little longer barrel (I think), and a very heavy double-action trigger. Mine work okay with FMJ ammo. If memory serves, they didn't feed the Bernaul hollow points I tried very reliably.
I think the Makarovs are more solid and reliable pistols. I enjoy shooting them more. Spare magazines are easier to find and cheaper for the Makarov. If I had to choose, I would certainly pick the Makarov. That said, if weight is an issue, or you like the Walther style, or you already have a Makarov, then there's no good reason not to get a PA-63. Both pistols are so low priced (or at least they have been when available) that you could buy the pair for around $250 or so.
Doug