I absolutely love K-Palette 24h Real Lasting Eyeliner Eye Liner. It stays on like a champ even if I accidentally get water on my eyes (from rain, etc.), but it comes off super easily by gently rubbing it with warm water.
I've been using Versailles no Bara Eyeliner lately since it's won a bunch of awards from Cosme (a Japanese makeup site that posts the best selling products in Japan), but it has no where near the staying power as K-Palette. Also, the brush is much softer so it's much harder to make a straight line.