I have a love / hate relationship with MAC, but they sure know how to make a lip gloss!
My ultimate favorite: MAC Clear LipGlass
This is the thickest, shiniest clear lipgloss I have ever used. It's wonderful. The clear is a lot thicker and shinier than their other lipglosses, so I use it as a topcoat to give color gloss pop. It also looks fabulous on its own. My only complaint is that the top always seems to loosen in my purse / makeup bag, getting sticky gop everywhere. I sometimes wonder if this is a conspiracy to get to buy a new bottle sooner.
Runner up: MAC Revealing Tinted LipGlass
Revealing is a rich caramel color. My favorite lip look is a nude lip made up of MAC Chestnut Lipliner, Revealing Lipglass, and Clear Lipglass. I never thought I could pull off a nude lip look before I tried this. Try it, you will love it.