This is a hard decision! I agree with Lollipop though: it will depend on which pony you can find that fits into your budget and is in the best condition. I voted Waverunner because, although I actually like all three ponies, her name is the coolest and more importantly to me she seems to be pretty hard to find with decent hair as the colour changing hair tends to frizz. So if the pony you have found has good hair and is in good condition otherwise as well, I would personally go for her.