Mid Lane Woes

While I think all of those would work, Chogath and Ahri are my picks. Both have ranged wave clear to help hold turrets and can do well in most situations. Ahri is safe to lane with and can roam very well to help your team, except takes time to learn how to team fight. On Ahri you need to use your ult to get on the priority target. For Cho, he has CC for your team in case they don't pick any champs with it. He is hard to kill and not many mids counter him.

If u want to master champs i prefer to master: Zed, Azir, Yas as my midlaners. But all of those have high skill caps, and i recommend playing unranked for now. but if u want some ez to play ez to win champs: Leblanc, Cho, FIzz, TF misc. (champs to play for fun): heimer, riven, lux AP champs to play ( strong far range pokers,but really squishy): Xerath, Malzahar, Karma