If you want (or need) a commercial/enterprise router for your home, you really shouldn't be looking at Asus: there are more appropriate solutions for you. I hope they're as magical and magnificent as you hope or believe they will be; I also hope you enjoy parting with your hard-earned money for the experience.
I'm running an ac86 for 2-ish years now, give or take, and havent had a single problem with it, other than with a couple of config blunders on my part. My experience differs from yours, obviously, because mine has been a rock solid piece of kit that I haven't hesitated to recommend to others because of that. Mind you, I'm just running a simple 2.4 and 5GHz wifi scheme, no guest networks, no VPN client/server, Native IPv6 on a 50/10 DSL, no dual wan, cake for qos, unbound DNS/blocking, no skynet, no suricata...no overreach.
I'll give you marketing: gamers trend towards the 5300s because they're explicitly marketed as Gaming routers to the gaming crowd, who then tend to come looking for advice on how to lower latency and find that their niche routers aren't as malleable as the mainstream ones. oh, the irony. right?
I also don't agree with you on the smart devices/IoT - 50 seems high to me: I'm doing whatever I can to limit my exposure to them.
Further, the ISP-provided modem/router combo box only does one of those acceptably well at any time for me (and many others), which is why companies like Asus make product in that category...and take them to a next step with tech like AiMesh. (I'm expecting v2 to bring home whatever runners are stranded out on base from v1 - a bit of patience might serve you well if youre so inclined - because alpha testers on both the factory and merlin forks are reporting improvements. by the time beta has wrapped and release is happening, it'll most likely be elegant/smooth or at least ridiculously functional for what it is)