My take on this is simple. It's what the market has right now that has risen above all others.
Before I tried an Asus router, Netgear routers were head and shoulders above anything else I had experienced, performance-wise.
After using the RT-N66U and seeing obvious gains over the comparable NG products back then, I ventured into using RMerlin's firmware. Best choice I ever made.
Not only was the Asus hardware the most performant possible. It was also the most stable, and most secure too (with each update).
Back then, I constantly compared stock Asus vs. RMerlin versions. Eventually, that got boring. RMerlin's firmware + Asus hardware was always the most performant, most stable, least glitchy, and most secure platform.
Fast forward to today, and Asus has gone above and beyond any other manufacturer with the support it gives Eric for his firmware. And, it is still head and shoulders above any other consumer router manufacturer with regards to secure code, applets, etc.
While I use and prefer Asus hardware and RMerlin's firmware and highly recommend it, I also appreciate the work
@Voxel puts into the Netgear routers he supports and I support him (and his users) just as highly, if only in spirit, today.
There has to be nectar to attract the honey bees. Asus and Netgear have that nectar for certain models.
All others are just 'me too' products with no soul or heart to them. I see them daily when I replace them with RMerlin-powered Asus routers (or suggest to the owners that Voxel has firmware they may want to consider to solve their network issues).
To my customers, I 'guarantee' the network will be noticeably better (faster, more stable, and more secure) than their old router. If it is not, I will put back their old network gear in place at no charge.
I know why I'm here. I want to share the best balance/bang for the buck I have found in the networking world in the last decade with as many people as possible.
Not because I have any agenda. Rather, that is how I also received (freely) the advice, tips, and procedures from the people who helped me first help myself and learn about networking and Asus routers in particular, and have allowed me to help others too.
Have you seen the forums for those other companies? If they don't like your question, it's deleted (and/or, you're banned). That tells me a lot about the company I (don't) want to do business with.