there are many different types of mid, the bursts and the constant damage champs. The best burst mages in game right now are vigar and annie. The best constant nukes in game right now are ryze and karthus. All these champs have relative low HP early game, but the trade off is when you hit level six, you can kill just about any champion with as low as 50 AP.

Personally i think ryze is the best AP middle because he can spam his Q level one. When im level 2 i just get snare, and by then they are 1/2 hp from spamming my Q alone. a simple ignite and flash to snare them and theres first blood. The only counters to this i would think is really tanky mids like galio and mord.

What do you think the best AP mid is? Pros? Cons?

i am best ap mid

There is no best ap mid, however I think ryze is currently really strong and so is Veigar at lvl 6.

Kassadin, by far in my opinion.

Luxanna or Kassadin.

There can be a lot of them, depending on who you are good with, and their subtle gameplay differences. Brand, Casseopia, Malzhar, and Morgana are all good examples of strong AP mid casters.

Personally I love my AP casters with skillshots, as those ones can usually hit behind minions without needing to hover your mouse over the other chamion for an extended amount of time(I use autocast), as well as not needing direct line of sight to use your spells on them.