I’m personally a huge fan of Lord of Chaos. It’s always a high point when I re-read the series. I really like all of the subtle foreshadowing of what’s coming up, all of the careful politics and groundwork that RJ laid for the latter half of the series, and then of course Dumai’s Wells is such an incredible moment in the series.
Lord of Chaos, 100%. AMoL is a close second. 10 years ago, I would have said that Crossroads of Twilight was my least favorite, but I thoroughly enjoyed it in my last reread.