I like THAC0 because it forces my brain to shift into an older style of play. With AAC I have a habit of subconsciously (and unfairly) comparing whatever game I'm in to 5e simply because of the mechanics. THAC0 really allows me to enjoy older editions and OSR games as their own thing.
I agree with this sentiment. I know people love 5e and PF because the interesting choices are when they build their character and deciding what feats and abilities work well together. I tend to gravitate to OSR style games because for me the interesting choices happen around scarcity of resources ( torches, food,money, hp, etc).
Playing PbtA games taught me that fictional positioning can have just as big an impact as mechanics. You can't wrap a mace around someone's ankle, but the chain of a flail...