Elobuddy is free atm, it was released few weeks ago, can't say much
L# : seems to get detected, doesn'T have to pay if you play just 2 normals per game, it's good
GoS : don't really know, think they got a ban wave ( ? )
BoL : You will get uttershit if you don't spend few hundreds..
I would recommend elobuddy or L#, though you still risk losing your account, better if you just play on a smurf with it.
Riot is actually doing something against scripters, so it's pretty risky on all platform, so be carefull if you decide to script.