Since the variants keep coming up, the two to actually get your head round are the ones where the rules change rather than the presentation.
Power Blackjack takes all the 9s and 10s out of an eight deck shoe, then lets you double, triple or quadruple down. Removing high cards is bad for you and the multiple down is good for you, and it lands at 99.54%. No Six Card Charlie.
Lightning Blackjack charges a fee equal to your bet, and after two consecutive wins you start getting multipliers of 2x up to 25x. It quotes 99.59%, the highest in the range, and that figure is calculated on everything you put in including the fee.
Those are the two best returns on the board and both of them get there by changing what a hand of blackjack is. If you want cards dealt out of a full shoe at honest odds with no fee and no gimmick, Seven Seat at 99.47% is the game and it has been sat there the whole time.