The best plane to get started with is the plane you want to fly most - it will be your passion to fly it that will help you learn any parts you find difficult.
Also I don't recommend any of the older planes, new planes are much easier to fly - there is a reason they all have stability computers and fly by wire :) Sure there are lot of systems in modern planes, but you don't need to touch any of them if you just want to fly.
Flying wise, by far, the F-15C is the easiest, it's a very low work load to just fly. The weapons systems aren't too hard to learn either, but there is a lot of strategy to learn in order to get really good so it's a plane you can pick up easily and it will keep you busy as you learn air to air combat.
Some beginners guides here: http://steamcommunity.com/id/tomlobster/myworkshopfiles/?section=guides