I have one OG APP1 pair and two APP3's. The 3rd gen is very good, but if I could choose, I would go with Gen 1 again. The pairing is fast, however I use them much less due to the crackling issue so I don't know how seamlessly they'd pair to several different Apple devices now. The pairing of the APP3 is flawless, but the comfort is better on the APP1 and, by extension, ANC, because ANC depends heavily on seal which depends heavily on fit, and that is better with the APP1.
Overall I don't regret buying two pairs of APP3's, nothing wrong with them, but if given then choice I'd buy APP1 with a fresh battery. They just rest more easily in my ear and the ANC isn't any worse in any way, shape or form. I feel like the ANC performance of the APP3 is overstated.