I think the reason vayne is so strong, is because her ult voids any lead you have on her.
I main Caitlyn, and if i go 4-0 on vayne, i will have a b.f sword and hurricane, while vayne will have stattik or phantom.. At this point when she presses R, she will gain (30 AD at level 1 )
Therefore i will only have a 10 AD lead on her from the 4 kills since 4 kills is what 300g each? = 1200g almost enough for a b.f sword.
Usually i'd have a cs lead but it ultimately depends on the support.
better wavecear and range/stun
pops her alive, also except draven, better waveclear
waveclear, intended being a scaling champion, attack speed steroid/poke even out the ad gain
even lane phase, better waveclear
doesn't have a build right now so don't even bother play
unrivalled waveclear
just afk farm and then afk push at lv7, don't even think about fighting/trading with your opponent
does good, similar powerspike as vayne
intended to be horrible early, a nightmare late