I have both the Sketch and Ciao Copics. They are the same colors the differences between the two are the Sketch hold more ink, are oval shaped and come in over 300 colors. The Ciao's are round, don't have as much ink and only come in just over 100 colors. The Sketch markers are a little bit more expensive than the Ciao, so if you are just starting out and aren't sure if the Copics are right for you I would suggest getting the Ciao's so you aren't putting out alot of money to find out you don't like them. The other thing with getting Copic's is that for best shading you should get colors that are with in the same color letter/family and at least a couple of numbers different, for example B12, B14, B16.
http://www.ilikemarkers.blogspot.com/ this is a great site to go to, to get alot of information on the Copic's. I went over the information about chosing markers before deciding on what to get, in the end I purchased as many of the Ciao's as I could and filled in the rest of the colors with the Sketch. The Copic's can be very addicting, but they are great for coloring. HTH.