I've just been through that process as I upgraded (smoothly!) to FTTC yesterday.
Decide what features you need then look for one that has them;
eg.
What link speed - 150/300 Mb/s
Do you need dual band (2.4 & 5Ghz) - 5G is fast but short range
How big an area do you want to cover - look for the dB ratings at different distances in tech specs
Do you need a guest network
Do you want usb ports on the router (eg. for shared drives/printers)
Do you want gigabit wired ethernet connections for a home LAN?
Manufacturers to check out are netgear, tp-link, linksys
Beware on Amazon and eBay - a lot of the bargains are old models.
I ended up buying a TP-Link WDR3600 from Tesco for about £50. Seems ok so far!
