I have used loads of different ranges in the past, but my first love and the one I returned to when I opened my first salon was Decleor. Ultimately it's you that has to be happy with the range, and it has to tick the right boxes for your business & clientelle, so no-one can really tell you what to use other than yourself!
The best bet is to get samples, talk to people, get your clients to try the samples as well & ask for their feedback. Also find out about minimum orders, marketting support, promotions, training, follow-up rep visits etc etc.