I'm pretty particular about my mascara, seeing as it's one of two products I use on my face (the other being lip gloss, natch). It can't clump, smudge or smear. My regular go-to tube is a little pricey at $22, but I've found a new mascara for a fraction of the cost that gets the job done quite nicely.
It's Jane Cosmetics' MaxLash Xtreme. It has a double-sided wand: one end applies the mascara, and the other end has a fine eyelash comb to separate and define your lashes, while also removing any clumpiness.
I'll admit -- I was skeptical at first, but it works, and I'm $15.65 happier.