Move to New York, best place to buy and sell bitcoins under-the-table.
Im kidding of course.
But on a more serious note, you can completely remove "Best US State" from the title. If you're making a living off selling BTC, then no state would be ok, because you're still under federal regulation as a money transmitter. You need to be registered with FINCEN, and have license in all states if you don't want any restrictions on who to sell to. Best move out of the country if you're going big with this.
This would probably be one of the better states to earn money from LBC (or other p2p bitcoin trades), assuming you are willing to take the risks of violating the law (which I would recommend against doing).
You would likely be able to have the highest spreads as both parties would likely be willing to pay a premium for privacy and the ability to trade bitcon when they otherwise cannot do so