I do my own shellac and have used Gelish as well- both $$ but great quality.
I bought a cheaper eBay brand- not so good!
Didn't last 1 week.

Gelish has heaps more colours than shellac, but I still prefer shellac.
With gelish, they advise you to buff your nails before application, I found that to be damaging.

Are you going to a salon or DIY?