Biloxi conditions
I have no idea about the 'best blackjack in the US', but Beau Rivage in Biloxi has an excellent 6-deck shoe game. S17, DOA, DAS, RSA, LS, and from what I see, between 1.3 to 1.5 penetration (slot in the shoe determines it, I think it looks less than 1.5). They have 2-deck games in the high-limit salon that I didn't watch.
Even at busy times, you can find $10 games, and there generally $5 tables as well. Beware, there are two pits, one in the front and one all the way in the back that have H17 instead of S17. Find the pit in the middle and you'll get the S17 game.
Also, in Biloxi, there are good 2-deck games at Treasure Bay, President and the Palace. All S17, DOA, DAS, NS, RSA at Treasure Bay. 50% pen at Palace and they use automatic shufflers, (not CSM or fake 2-deck), but 60% at TB and President.
Good luck.
GPC