KO vs AOII
AOII is better, but ZG is suggesting that you learn a simpler count. I disagree that KO is the way to go because it's based on the running count. That means you should learn different index numbers for different deck games, lest you want your performance to suffer a little more. ZG made an earlier suggestion that I agree with: use Hi-Lo Lite (Snyder's Blackbelt in Blackjack). This way, you only have to learn 1 set of index numbers. Usually the harder the system, 1) the slower you'll count 2) the harder it is to learn and 3) the more likely you'll make mistakes. Hi-Lo Lite is not without some benefits: 1) rounded matrix, 2) "upgradeable"--shuffle-tracking and such. All in all, it depends on you. If you want to play strictly SD and you have an aptitude for numbers, then maybe AOII is the one for you. If, however, you want something a little weaker (which you can make up for in more hours and less headaches), then maybe KO or Hi-Lo Lite is the way to go.