So you recommend Coinbase to get bitcoins to use gambling? Isn't there a fair chance Coinbase will close your account if you use it towards gambling?
I don't recommend violating anyones terms of use -- but speaking purely about bustabit privacy features: Bustabit's uses a custom coin selection for deposits/withdrawals that makes it considerably harder for anyone to know if you're using bustaibit or not. It's not fantastic, but it's decent.
In the next release though, it's going to get pretty damn good.
Our new algorithm (that has like >1 month of development time put into it, and uses a full on cutting edge constraint optimizer) will make it
very hard for anyone to distinguish a bustabit address from any other. (although there's still a bit of things I need to figure out, like sending transactions over tor incase there's a spy node recording that I'm the probable origin of the transaction)