Masteries and Rune Remember System
It's a small change, but it would be nice if you only had to choose which masteries and runes once for every champion you play. Plus it would sometimes means the different between life and death, if you forget what to run and dont have time to check out a guide. Or if you really had to go on the toilet or something like that while in que.
Of course it has to be user friendly, so you always can change it, if needed in special circumstances.