Bitfinex has the most complex and advanced trading tools I have ever used. With their advanced UI, I can use their charts to perform RSI and MA searches as well as they have very good indicators. The second-best thing I like is P2P funding which allows me to margin trade without wasting too much time on getting funds from outside. I love their shorting feature which I use most frequently. I wish they reduced the $10k limit to deposit which caused me to not use it but now I love it. It would be great to have a troll box or a chat with all users online.