Everyone pretty much has their own way of using gel liners (or gel pots to some). Although most use it as their regular eyeliner, I personally enjoy using them for my waterline. Now this isn't the proper use of gel liners, but most use it for this anyways, since it does work. Most that I have tried manage to stay on my waterline far longer than any waterproof eyeliner pencil. I had tried 3 different brands so far and only one takes the cake when it comes to water resistance: L'Oréal's HIP.
I tried Maybelline's eyestudio pot liner and absolutely regret the purchase. Although I'm sure their liner is easy and wonderful for regular eyeliner use, it didn't pass the waterline test. The product came off minutes after application.
The more shocking failure was Stila's smudge pots. Now this is rather disappointing, considering Stila cosmetics are awesome and are reputed for their smudge pots. Well, like Maybelline, as I'm sure they do wonders as regular eyeliner and even as an eyeshadow base, they too failed the waterline test. In fact, the smudge pots were a challenge to apply. The product basically brittle's instantly once it touches your waterline and ends up everywhere in your eyelashes. I felt instant irritation just by trying to get the product on, and not as an allergic reaction, but just from playing around my waterline too much with it. Although, I will admit, for whatever amount I had managed to apply, the product sticks on VERY well, but the application was too annoying to bare to attempt ever again :'(
L'Oréal's HIP color truth cream eyeliner kicks absolute waterline ass. The product is simple to apply and stays on for long periods. It's the only gel liner I am able to bare and swear by (until I find better :3).