I have never had any problems with bitfinex, I have been using them for past 2 years now. They are the best support providers in the industry and their features are so advanced compared to other exchanges. I regularly use the feature of margin trading which compared to other top exchanges is fast. I would love to see new features in Bitfinex. The UI and charts are some of the most detailed ones. I would really suggest you bitfinex if you want to become a professional trader. You will not face the pump and dumps of other exchanges here.