[Editor's Note: The following answer is penned by the unrivaled Arnold Snyder, publisher of the venerable Blackjack Forum, author of a number of blackjack books including the best-selling and "underground gambling classic" Blackbelt in Blackjack and The Big Book of Blackjack, content manager for our sister website ToplessVegasOnline.com, novelist, memoirist, essayist, reviewer, and all-around man about town and cool character (and he's very kind to dogs). We're all extremely fortunate to have Snyder (as he's known hereabouts) as a member of our list of QoD experts and, for all intents and purposes, extended family.]
This isn't an easy question to answer, because "easiest to learn/use" and "most accurate" can be misleading descriptions.
For example, the easiest system is one players used back before the first card-counting systems were published. You watch for aces and if you go halfway through the deck without seeing one, you raise your bet significantly.
Unfortunately, although that system could win money in the single-deck games dealt in Las Vegas in the 1950s, you’d be unlikely to get an advantage over the house with it in any of today’s games. And if you raised your bet enough to get an edge, you’d be quickly identified by the casino as a counter.
Likewise, Ken Uston (a famous blackjack player, strategist, and author, credited with popularizing the concept of team play), once published an "ace-five count," in which you add a point for every five you see and subtract a point for every ace you see and any time your running count is positive, you bet more. The problem with this count is the same as the problem with just watching for aces and betting when the deck is ace-rich. It’s a valid counting system and easy to learn and use, but it’s so weak you’ll never make money with it and you’ll likely be identified as a counter if you attempt to raise your bet enough to beat the house edge.
So, I’ll assume you’re more interested in a system that’s relatively easy and potentially profitable. My advice would be to look at either the Red Seven Count or the Knock-Out Count.
You can find the simplest version of the Red Seven Count on my website.
You can find the Knock-Out Count in the book Knock-Out Blackjack, published by Huntington Press.
As for the most accurate card-counting system, we have the same problem in reverse.
Peter Griffin, author of the seminal The Theory of Blackjack, developed a system where you balanced the 3s, 4s, 5s, and 6s against the ten-valued cards and kept separate side counts of the 2s, 7s, 8s, 9s, and aces. But I don’t believe any person with average math ability could learn or use this count system in a casino.
Plus, Griffin's system is ideal for deeply dealt single-deck games, which don’t exist much anymore.
As for more accurate systems that are also practical, there are many "advanced" counting systems: Uston’s APC, Bryce Carlson’s Omega-3, Wong’s Halves Count, Snyder’s Zen Count, Hi-Opt II, Revere’s APC, and others. But most professional players steer clear of these higher-level and/or multi-parameter counting systems, because they’re more mentally fatiguing and more likely to cause errors.
You can find dozens of articles about blackjack counting systems, with mathematical analyses and comparisons of systems using computer simulations in the Blackjack Forum Library.
