I've always used just a regular eye liner pencil to line my eyes, but I am in love with a new product!! I've noticed for my work I've slowly started using the gel or cream liner on my clients....because I LOVE how it applies soo much better than the pencil! A lot of times I experienced no product coming off, very little, or tugging as it "glides" across the eye. I know personally I hate having my pencil tug at my eye as I try to apply, so with my clients I generally grab my cream liner first!
There are a lot of different gel/cream liners out there - some come in single pots with the color you use most frequently; and others come in multiple shades (less of each) to give you more variety. Currently I use Smashbox's eye liner palette.