I have never used either- and they are both annoying to get killed by. However i find marty quite cheap - no skill involved, just a dropped grenade. It almost awards you for dying. Last stand annoys me ALOT becuz i never expect it. It is not so much cheap , instead it just outsmarts me i guess. I wouldn't mind the perk if the person in last stand died after like 10 seconds, but i hate it when you shoot some one , and then they go to last stand and kill you, and you don't get the kill.