My favorite brand depends on what my mood is at the time. If I just want good, basic, no-nonsense absinthe with a rock-solid flavor and nothing exotic, then La Clandestine is the one I seek. It's the blue bottle, fourth from the left.
If I'm happy and the weather is hot and I want something cool and refreshing, then I reach for Vieux Carré - green bottle, second from the left. It's a bit lighter than most and a tad minty.
If I'm feeling creative and/or analytical, St George (last bottle on the right) has enough layers of complex flavor to keep me entertained and enthralled.
If I'm feeling beat down by the world and just need something to get my mind off it - or to help me brood about it - then Mansinthe (fifth from the left) is good for that. It's a bit jeckyll/hyde, though. If your water ratio is off it can be subpar, but when you get the right mixture, it sings.
Not pictured: Abyss. This one is the poster child for "acquired taste." When I first got it, I described it as "vile." It's excessively bitter and tastes like liquified pith from a grapefruit. I could barely choke down the first glass and the second one (weeks later) wasn't much better. I kept at it, though, and by the time I got halfway through the bottle it had become one of my favorites. I wouldn't recommend it early in your absinthe exploration, though. It's a tough nut to crack.