It's been my experience that the key to successfully applying cream/gel eyeliners lies with the brush. I've had to go through quite a few before finding one that I can use with ease and precision.
The best one for my eye shape and the looks I prefer is without a doubt Sephora's Professionnel Pointed Liner/Eyeliner Brush #17. It's probably the best $11 I ever spent on an eyeliner. When I originally purchased it, I just wanted it as a super precise concealer brush. ...and I needed to spend another $10 to get free shipping...
But once I got it, I decided to try it for it's actual intended purpose and I have never looked back. I can apply MAC and Clinique gel/cream liners with just as much ease as any pencil eyeliner and I've finally been able to get perfect, pointy winged eyeliner without throwing a temper tantrum and chucking the eyeliner brush across the room. I like how skinny it is, because I don't always want a thick line - especially on the inner part of my eye. The only thing I don't like it for is trying to tightline or line my waterline. Because it's sooo fine, the brush actually tickles!
Before I found the wonderfulness that is Sephora's eyeliner brush, I was using the Buxom Lashliner Brush. I originally purchased it with the Buxom Lashliner cream liner (you know - the one that's supposed to condition your lashes and make them grow faster/prettier/healthier? Since it transferred like crazy on me, I never got to put those claims to the actual test...) The brush handle is slightly shorter than the Sephora one and the bristles are a little thicker, making it ideal for tightlining/waterlining for me. If I know for a fact that I want a thicker line, I'll still grab the Buxom just to cut down on time, but 95% of the time, I'm reaching for my Sephora one. Still, the $15 I spent on the Buxom one wasn't a complete loss.
I cannot say the same about Sonia Kashuk's Bent Eyeliner brush, however. I hunted high and low for this stupid brush, because all of the makeup boards were going absolutely ga-ga over it. I shelled out my $6, took it home, ripped it open and tried it out. I was very, very disappointed. I know people love this brush, but for someone with smaller eyes (me!) it's a nightmare. I understand the premise of the "bent" angle, but for me, it was awkward to figure out which way the angle should be. The brush is thicker than the Buxom one, which meant I had a hard time getting thin lines and it seemed to make the product skip and drag along my eye. I know it's not the product, because I've used the previous two brushes and I haven't had any problems. I love a majority of my Sonia Kashuk brushes, but this one? Not one bit.
The next two brushes I was fortunate enough to get as part of a special edition miniature set from my local Cosmetics Company Outlet. If I had paid full price for either of them, I would have been beyond peeved.
The MAC 266 Small Angle Brush retails for $19.50. Upon looking at it, you'd think it would be perfect for creams/gels. Sadly, that's not the case. I think it's better for doing your eyebrows. For me, it was way too thick and glopped the product on unevenly. It wasn't as pointy as it looks in the picture and it was way too hard to even or thin out the line. Like Sonia's brush, there are some people that absolutely swear by the MAC 266, but I would much rather pass.
I'll also pass on the MAC 212 Flat Definer Brush, coming in at a whopping $21. Beau Nelson, the founder of Beaute Cosmetics and Kristin Stewart's makeup artist of choice, had suggested using this type of brush for tightlining. Mmmkay, Beau... It's much easier demonstrating on a model than trying to do it yourself, apparently. When I tried following his technique, I ended up poking myself in the eye. I don't have the tiniest eyes in the world, but this brush was impossible to work with. It was too wide, too stiff, and made applying liner an awful mess. Tiffany D suggests using this type of brush to brush on different colored cream liners over your mascara, as opposed to buying the different colors in mascara form (a la, blues, plums, sparkly, etc), but I learned that tip a little too late and had already swapped away this stupid brush for something I would actually use.