Too many options to count
No pun intended. Really, this is actually a choice for you to make. All real card counting systems can get you an edge over a beatable game, but the medium or system you count with is up to you. There are level 1 thru level 5 counting systems that can all beat the game, but it depends on how much work you want to put in to it. A great reference for a comparison between all the systems can be seen in the SCORE section in Don Schlesingers Blackjack Attack 3 (BJA3). If you don't have it, I suggest reading the SCORE section before picking a count system and thinking about what level of attention you can maintain in a casino.