I guess its without a doubt Primedice. But if we leave Primedice alone, who is the heir of the throne. The prince of the bitcoin gambling kingdom?
Maybe try Win88 Casino. They have chat, invest, 2k satoshi faucet.. Primedice is no doubt the best but for those who do not have any, win88 is the way to go. 2k satoshi faucet is a lot better compared to PD. lol