I didn't care about any of this (my off the shelf Router used .local) and then I started selfhosting more and using pFsense as a router OS. It defaulted to using home.arpa, which was so objectionable that I spent time looking into RFC 6762 and promptly reverted to .lan forever.
The official choices were: .intranet, .internal, .home, .lan, .corp, and .private. LAN was the shortest and most applicable. Choice made.