Suggestion: Give ADC's more base AD and AD/lvl
But much less base AS. Like, .525 being the standard, down from .625. The best balance might be an even lower number than that.
My reasoning:
On one hand, I don't like the ideas that all marksmen stomp on everything come lategame when they're already great at taking objectives.
On the other, when I get shot by a Caitlyn I wanna feel more like I'm getting shot. I shouldn't be able to shrug that off with lifesteal and Masteries by the time I've cleared a minion wave at level 1.