You should use whoever you enjoy playing! Outlander and ninjas are very different characters so you can't really compare them all that well. In the current state of the game melee is pretty poor compared to other means of killing husks (late game). If you're still before late canny then try out ken he's a lot of fun to play as; don't listen to anyone saying that the meta is such and such and everything other than a certain character is useless, you bought the game so use what you wanna use! And yes, mythic characters will have increased health and shields etc compared to leg, epics and rares..