counting...
I started with Hi-Lo. I've stuck with it. For probably several reasons.
1. It is simple enough to do the actual counting. When I looked at a couple of other options, particularly those that have a irregular "pattern" (ie red-7 means you don't count all the 7's, or an ace-neutral count usually excludes 2's and aces, etc, I decided that Hi-Lo would be the easiest to learn, practice, and get very fast at. I find it easy to count 2-6 and 10-A, with very little thought.
2. I found several online references to Hi-Lo with suggestions on how to practice, etc (unfortunately none of them mentioned CV blackjack, something I have just recently found, and if you are just starting, it is beyond worth the money, for the drills, not counting the actual game play it provides). With plenty of resources, and with many people using hi-lo, it seemed like a good place to start.
3. I wasn't put off by the TC conversion. A little training and you can read the discard tray very accurately. CV Blackjack can also help there although I don't find it quite as realistic since you are looking at a monitor/flat-panel which is not quite the same as dealing with 3d-space pattern recognition mentally.
4. I can use hi-lo for 1d through nd games. TC at 1d is a bit messier, but I don't find it that hard to multiply by 4, 2 and 4/3 using 1/4 deck accuracy. For 2d I usually use 1/2 deck accuracy, and for 6d I use 1d.
The main thing for big deck games is betting correlation, and hi-lo (and others) are very good. playing efficiency is lower with hi-lo, but then again it is lower with the unbalanced counts as well. Once you get surrender and insurance indices mentally fixed (again, CV BJ will drill you until you can do them blindfolded, which is a good trick since you can't see the cards. :) ) then you have gotten more than enough to play with reasonable advantage. Betting is most important, and surrender/insurance are next on my list along with what Don calls "the illustrious 18". Trying to memorize all the hi-lo indices is a daunting task if you don't play regularly, which I usually don't although I have been playing a bit more than normal the last two months or so...
My advice to anyone is to learn a count, practice it to get your speed up, and then use it effectively. I _still_ favor 2d games so your counting system needs to be reasonable there. There's a great deal of difference between playing 2d and 6d from an hourly wage perspective. But in 2d, you need to get all those 2-card counting drills done, as when the dealer gets a 10-up and an A-down and he flips that Ace over, everyone will toss in their two cards at once. If you can do the 2-card drill (cancellation) well, you will have no trouble, and the rest of the game is trivial to count once you get the idea of how the dealer deals, and how he pays, and you learn to not count the same card twice which can be confusing at first...
The thing I like about Hi-Lo (or other balanced counts although this is the only one I personally use) is that my playing indices are based on a TC that is calculated the same way each time I play, regardless of the number of decks. IE my IRC always starts at 0.
However, this is somewhat like programming languages in computer science, some like X, some like Y. IE C vs ADA. I'm quite capable of doing anything I want/need in C, and therefore I stick with it. Same for Hi-Lo... You'll probably learn to feel the same way about KO or whatever you end up choosing. I would not bounce around too much however. Better to be a master of one as opposed to a mediocre player of all...