A lot of it is tied to how much work you're willing to do, and sometimes how flexible you are on replacing scripts due to compatibility issues.
I used Falcao's Pearl ABS for a while - it's very user friendly, has a truckload of customisation options - more suiting for me than XAS - and was pretty easy to get running. It also works with icons rather than character poses which can save a load of time if you're not artistically inclined. XAS came with a whole ton of compatibility errors for me, and the interface that comes with it is so obnoxious too, which led to me to tons of GUI editing and whatnot. It can do some cool things though, but I much, much prefer Falcao's system, generally just for the ease of use and the fact that it has most of the options that XAS does too. Though I haven't done an actual side-by-side of them, I'd recommend Pearl.