I think poloniex and bittrex is best trading sites for all but great information for me about
Shapeshift.io
Gatehub.com
shapeshift can't handle huge transactions/exchanges.
Gatehub.com is quite new to scene but most of ripple holders are using them.
Poloniex is having lots of issues lately specially with their withdrawals so better to avoid them to store ripple right now.
The only option left right now is bittrex and I am trusting them with all my ripples and other alts.