It will be my main router.
What are you basing your opinion on?
my humble opinion = (x number of years of experience + x number of years of education) x (a bit of arrogance) minus knowing that other people may be occasionally correct.
a home router in the $30 range is usually the bottom of the price range. A decent router can last you a few years so don't be too cheap. unless it's a big sale or some kind of deal it will be more than $30, perhaps between $50-$100.
In other words how do I know which router is better than the other?
https://www.cnet.com/how-to/things-to-consider-when-buying-a-router/You mentioned large house.
How many devices are you connecting?
Speed needs?
Netflix streaming?
Voip?
Do you want to connect a printer? The router can be your print server.
etc, etc
and most importantly: can you install a non stock firmware such as dd-wrt or merlin on the router?
Just rely on if it's more expensive/new that means it's better?
definitely not, but newer routers may have new features that you may need.