Basically alls Color Gels can be used for Nail Art. It just depend what you plan to do.
I love the Color Gels of the Company Catherine. But Cal Gel color Gels supposed to be good as well ( I don't use it so I just can tell you what I have heard)
I like to do flames etc with Color Gel that I can apply very thin but in the same time it covers all up. On this way the color Gel don't has any effects of side lines. If you have to apply a lot of Color Gel on the Nail to make it cover , most of the time it will ruined the shape of the nail
So my advise: look for gel thats thin but also covering