not my area of expertise.
The problem is that I am a hi-lo user. That is all I have learned. Yes I might be able to count down a deck/game using (say) KO since I have looked at it, but that is all I could do. For Hi-Lo I have learned by lots of practice (particularly with CV Blackjack) to rip through the cards almost sub-consciously. And I have learned the I18 (and fab 4) indices plus a few others that CV blackjack has included. So I really have no way to compare them. There are plenty of others that can answer this, of course. I can really only answer that which I know something about.
Hi-Lo works. lots of people use it. There are other counting systems, plenty of them in fact. As the old saying goes, however, it isn't so much which one is best, it is which one can you play the best? 1-level counts seem best unless you really play often, and for short sessions, at least according to posts I've seen here. Multi-level counts have a better playing efficiency, but are harder for some...
This is probably best answered by the classic "play within yourself". IE do an honest assessment and after looking at the systems, pick one you believe you can _really_ jump into and get down cold. You can't be thinking about counting, BS deviations, BS in general, totalling up your hand, etc. Something tells me that it is better to start off simple and move up, rather than start of complicated, fail, and move down.
YMMV. One going point for Hi-Lo is that most everyone can give you advice about it, and if you talk TC with someone you are on the "same" page...