A S&W 642 and a makarov are both in my carry rotation. If I had to chose just one, it would be the 642 only because I need to pocket carry often.
In my backyard ballistics testing (wet phone books) the makarov had better penetration than the 642. Its been awhile, so I don't remember the ammo I used in the 642, but the makarov ammo was the cheap silver bear 95gr. Buffalo Bore offers a 115gr. hard cast flat nose for the makarov. Thats what I carry.
If I could only carry 4 rounds in my 642 and didn't need to pocket carry, I'd go with the makarov.