You'll have to forgive me for not being able to answer that question briefly.
I'd say I have several reasons why Angel's is not my cup of tea. There's the combined ores, of course, but that's reversible. My bigger problem is the general design philosophy. I may have named my mod "More Stuff" but Angel's adds soooo much more stuff. Everything is so convoluted. There are just tons and tons of chemicals, many of which are only used as an intermediate step to produce a single other chemical, because why do something in one step when you can do it in three instead? And while their ore processing scheme is very impressive, with lots of real-world concepts all implemented to maximize, maximize, maximize your resource output, honestly I find it all unnecessary, and each of their merged ore production chains feel kinda samey. Even the bioprocessing stuff, which I love the concept of, is still so difficult to parse and remember due to the excess of redundancy.
But the weird part is what comes after. All of that complexity is for the most part just to take you from stage 0/stage -1 materials (raw ore/combined ore) to stage 1 (metal plates). As far as intermediates and finished products go, aside from the added complexity of the chemical precursors, the recipes at these stages are barely touched. Making an assembler is so trivial compared to making a simple iron plate during the endgame that it feels massively lopsided. I'm aware of the components overhaul that's currently in development, but from what I've seen of it in the current version, it looks just as overdesigned as the rest.
I also find some of their design choices to be a little too "eh, whatever." The synthetic gems are the worst offender in this regard, specifically in how they're all identical. They could have done much better. I was able to throw together some synthetic gem recipes that were mostly accurate, though I did have to cut some corners since I didn't have beryllium or chromium. But Angel's does have chromium, except it's only used to make more iron, titanium, or steel. I feel like they could have, should have done more with it. Perhaps they didn't want to make any disruptive changes in that production chain, but it feels like missed potential to me. I guess we all have our own standards of what is and is not an acceptable shortcut or break with reality. And speaking of missed potential, one of the bioprocessing chains involves breeding biters, but you can't deploy them to fight for you like Bob's drones? It would literally take a single line entry in the lua files to make this possible. Then again, Angel's is very much geared towards pure factory building, so it may be intentional.
In summation, Angel's is just too overdesigned for my taste. The layering of steps, unnecessary redundant recipes, lack of completeness in some areas, and gameplay imbalance against combat and exploration altogether doesn't give me much reason to want to play with it. I prefer the more economical complexity of Bob's, or the buttery smoothness of Krastorio 2.
