The best mascara I've ever owned was the YSL Effets Faux Cils, so I have to agree with Max on this one. It's extra-volumising and so easy to apply, and looks stunning. Well worth the spend.
Oh, and here's a great tip for using mascaras:-
DON'T dab the brush in and out of the mascara tube when applying your mascara. There is no need to do this as it makes no difference to the amount of mascara on the brush. What it will do though is pump more air into to the tube which in turns gunks up the mascara more quickly.