I'll even include Hope Summers (since it looks like shell be sticking around after second coming and newest addition Crosta
 

HELLION!

X-23 and Hellion ( their names alone make them badass)

I like a bunch of them. Anole, Gentle and Pixie are great for having gone from simple background characters to actually interesting, granted they changed Pixie a lot. I really enjoyed Prodigy and Surge in New Mutants and want to see more from Trance. I also hope they'll end up doing more with Cipher since it was left dangling that she's hiding from someone but Young X-Men ended before they could say who or what.
 
Its too hard to just one so I picked like half of them. Heh. As for who's the most powerful....I'm thinking Cipher since she went unnoticed for months she could have killed any of them in their sleep. As far as powerful output or strength of their abilities its probably Elixir, Hellion, Ink or the Cuckoos.

I would have to say Gentle.  
You could never go wrong with Nez :]

" I would have to say Gentle.  You could never go wrong with Nez :] "

It is also stated that he has potential to be one of the strongest people on Earth, but it's his limited capabilities that take that away. I think it is better this way, so he does not become another generic character with extreme strength. 

Anole. Bling, Trance, Loa, Pixie and Indra all come second lol.

1. Hellion.
2. Elixir /X-23.
3. Mercury /Dust.
4. Rockslide.
5. Prodigy.

1.  Anole 
2.  Pixie 
3.  Hellion 
4.  Wind Dancer 
 
Most powerful: Pixie.  Magic always is, which is why I hope she loses those abilities.

Rockslide, X-23, and Armor are my favorites :D

Fav= X-23
Most powerful= Hope summers