magic and power cosmic are different for marvel and dc. since power cosmic really only exists by name in marvel im assuming its marvel ur talkin about. so for that i say magic for the most part as ive seen even galactus tremble before dr strange. and surfer would be beaten easily by most magic users like sky fathers, mephisto, dormammu, shuma gorath, thor. etc not to mention dr strange but then comes cosmic power like that of eternity death and other abstracts which is somewhat mixed with magic specially for master oder, lord chaos, inbetweener etc.
and theres also the the infinity gauntlett which looks more magical than cosmic and LT was resisted by stranges mystical power so dunno. magic is basically from the eternal vishaantis which seem to be more powerful than ur normal abstracts like eternity. but at high levels its all mixed up. normally though {at lower levels when it IS distinguishable} id choose magic cause its more powerful cooler and has much more CHARACTER to it as opposed to the pliable power cosmic. unless ofcourse ur talking about genis vell whose is the only cosmic power id LOVE{and the power of the fallen one-first herald} to have.{i think uber psionic power like franklin, wanda, jean is a combination of both cosmic and magic }
magic characters are also more plenty dr strange, thor, loki, odin, gaia, zeus, hercules, dracula, strange, cuttorak, zom, mephisto, shuma, dormammu etc
while only characters which are EXCLUSIVELY power cosmic are galctus and his heralds while others like thanos use a combination of both and their powers remain somewhat undefines in their true form of clearly originating in mystical, cosmic, psionic or scientific.