17 & 18 do not have the same personality. 18's all like, let's just fly to Goku and get it on with it bro, 17's all like, don't be a boring bitch let's still a van and do some off-road driving to find his place. Have fun with it sis. 18's all like, capable of gauging her opponents and runs away from Cell, 17's all like Saiyan, overconfident and like I can beat this bro. 17 cares about wildlife, 18 cares about money. 17's enjoys fighting, 18 only does it for the prize money. If we had to keep only one of them . . . I'd probably go 18 just so there's a female fighter in the main cast, but if it wasn't for that, 17 all the way.