Router for Arris S33? - eviltoast

Hey everyone! My girlfriend has xfinity 1200mbs internet but her hardware is seriously outdated (10+ years old) so I’d like to surprise her family with a new modem and router to really boost their internet performance as they don’t get anywhere near the speed that they’re paying for. After doing some reading, I decided on the Arris S33 modem but I’m struggling with which router to get. She doesn’t need a fast LAN speed, I think her and her whole family just use wifi and I’m trying to find the best router option for them to all get 1200mbs wifi. Any recommendations / advice? Thank you to everyone who took the time to read this.