I think I've covered a good price range of liners here, and these are the best ones that I have used.
1) Maybelline Eye Studio Lasting Drama Gel Eyeliner- This product is great if you are just testing out the waters with gel liner, and don't want to spend 20+ dollars on your first pot. Its cheap, and it even comes with a brush (which I actually don't like too much- but it isn't awful, which is saying a lot). It comes in 4 shades, and you can buy this at any drugstore, Wal-Mart, or whatever for under $10. It is indeed long lasting, not the smoothest texture (but far from bad), and dries quite quickly. I will say, if you make a mistake and need to clean up your line, it is so hard to do so with this liner without making a bigger mess.
2) Clinique Brush On Cream Liner- My personal favourite of the bunch. Pricier than the Maybelline, but honestly not by that much. This goes on beautifully, such a smooth texture. It makes drawing your line so easy. It does not dry out in the container, lasts long on the eyes, and just great to work with. There isn't really anything bad I can say about this product. Also comes in 4 different colours.
3) MAC Fluidline- Another popular product- I don't own it, but I hear about this all the time. Comes in 6 shades, and goes on silky smooth. Comparable to the Clinique liner. Although, I have been told that if you have oily eyelids, you will need a base underneath (which I don't find to be true with Clinique), or it might smudge- not a good look for anyone.
4) Bobbi Brown Long-Wear Gel Eyeliner- Coming in at $21, this is the most expensive liner so far, but I've heard nothing but good things. It also comes in the most number of shades (8). Although, I'm not sure that its any better than Clinique or MAC- I don't think I would pay the extra $$ unless I wanted a specific colour.
Lastly, when you're looking at liner brushes, I would recommend a fine brush, especially if you don't have much experience with gel eyeliner. You can keep the line thin and simple, or go for thick and dramatic with any one of the following brushes:
MAC 209/210, Sigma E05, Quo Angled Eyeliner Brush, Louise Young LY23-25, Sephora #17 and Becca #6.