Doesn't have to be. Just go to smallnetbuilder's router ranker, sort by overall ranking, or (since you were having performance issues) sort by routing performance, and go down the list until you hit your price limit.
It's not quite as nerd-gratifying as making a well-educated selection based on all available information and consideration of every possible use case, but the chances of you making a bad choice are essentially nonexistent.
Incidentally, the R7000 you had also has a fairly beefy dual core CPU, but only 256 MB of RAM. Are you doing a lot of torrents?
I'd be curious how any of the above would compare to a RasPi 3 (quad core, 1GB RAM) running pfsense though. You know, if you were feeling really, really geeky.