Bobbi Brown Gel Eyeliner > MAC Fluidline, hands down.
Fluidline ran a lot for me. Actually, I hated that product. BB's liners, on the other hand, stayed put all day but were easy enough to take off at night with a little cleanser. Gorgeous, subtle colors, too!
I recommend Laura Mercier. Try to get to the counter if you can and have them show it to you with the flat brush.
i also have the Bobbi Brown which I am still practicing with and really have to get the hang of it. I purchased it on an international flight with no make-up person to help me out. Any suggestions? I keep forgetting to go to the counter and I am not sure if they'll help me or not since I already have it.