we need trex. I don't trade in any of those sites

I don't think that Trex does any asset type of coins - and I believe that Storj is currently a part of CounterParty (clarification)?
Not sure why Trex won't do that; there are plenty of good coins that they are missing out on...
I recommend Poloniex from the list above. In many ways, it is better than Trex in my opinion...the only relevant difference is volume (but Storj volume is pretty large on Polo).
Bittrex does not currently list counterparty assets like SJCX. The Storj Team has already contacted Bittrex about listing SJCX, but it would be up to them to make the necessary adjustments in order to make SJCX listing possible. Most likely, this will happen in time as the Storj project progresses and gains acceptance.