should I rank up my 4* rank 4 archangel (awakened) or 5* rank 2 old man logan (not awakened)??

OML has a nearly nonexistent regen rate, only bleeds on specials (which still does measly damage for a bleed), and berserk is only active for a very short time, and takes quite a while to get back. AA, on the other hand, does pretty decent bleed and poison damage, especially at the high rate that he applies them, and neurotoxin is insane in terms of damage.

I would also like to note that OML is bleed resistant, which is useful for skill defenders, but as the AI aren't really supposed to get more than a few hits on you, this is pretty much pointless. As a defender, this is also pretty useless, as most, if not all, of the high tier techies don't apply bleed, and rather rely more on utility (Ex. Stark AI evade for SE spidey, tactician for SL).