As I've only played EW seriously and into end-game, I don't have any experience with the previous iterations of AST, even if they all sound more engaging, skillful, and fun. However, at the moment I am enjoying AST the most out of the healers due to its more brain stimulating gameplay compared to the other three healers. You actually have something to do outside your ''111111111'' rotation and the 3 cards + divination + lord crown + earthly star window every 2 minutes is very fun for me. That incredibly tight and busy window is pretty much my cope right now for healer design lacking an actual dps rotation. All of it's healing need to be pre-planned which requires active thinking (unlike WHM, just turn brain off and press button when needed) and it has the most interesting healing button as well, with Macrocosmos. Neutral sect is a big benefit too in tight situations or when you need to cover for your shield healer (PF experience of incompetent co-healers go crazy).
It still has flaws of course: Card RNG is such a kill joy at times, especially with Lord/Lady where I will never get the one I actually want for a given situation. Lightspeed is basically a must-have for the 2 minute window for optimal card usage (3 cards + divination), leaving AST as the most immobile healer where certain mechanics make you have to move a lot, OR if you decide to save LS for those mechanics you are hindered on your optimal 2-minute window. Obviously, the lack of more dps buttons is a problem too as outside the 2 minute window, and one card draw 30 seconds from your last divination, you are going back to spamming 11111131111 for an extended period of time. It's also garbage at recovery situations, especially when progging savage as it has no on-demand burst healing like WHM.
The upcoming rework is making me worried, because whilst AST, is definitely not as nuanced and full of depth as it used to be from my understanding, it's still definitely the hardest healer by far and the only one which has an engaging job mechanic that takes genuine effort to pull off optimally every 2 minutes, as well as a clear and differentiated role from WHM. Comparing SCH/SGE and seeing how similar they are in so many ways.. yet you look at AST/WHM and they're extremely different to one another, and that's very good IMHO. I'm terrified this rework will just strip away the remaining complexity and ''depth'' of AST and simply make it a WHM with a star/galaxy aesthetic, as every rework seems to make it more simpler and easier.