Hey, I'm a current AP Mid for a team and I would like to give you some advice on laying out your requests.
Firstly, you generally should try to be more proficient with a larger magnitude of champions. Sure, having a few you're absolutely best at is amazing, but having a list of champions in order in which you're best with is even better! I can effectively play every single middle champion, but I can only play 6 or 7 with absolute dedication and knowledge of what my limits are. Secondly, you're primary champions, for a ranked team, should generally be powerful ones that fit the meta. Fiddle is a solid choice, but Lux has more-or-less been reserved for the Support role for some time. She lacks much late-game damage that APCs are expected to pump out.
Secondly, you should follow one role and stick with it. I can play every single role well. But if you set me behind mid or support, or any primarily AP role, and I'm going to just totally dominate. That's my fortè. AP Champions.
I'm not trying to insult or start a flame war. I'm just trying to give you some advice to make finding a team easier. C:
Good luck in your search!
Team exHUME Co-Captain, armaGEDDY