Not sure about your specific use cases, but the UDM (and I'm guessing UXG), are lacking a lot of features former UniFi (USG) products had. Most notably, no way to do custom configurations with JSON files anymore. As far as I know, there's no multi-VLAN support on the WAN interface, so that excludes those of us with IPTV that rely on VLANs and IGMP/Multicasting (Bell Fibe for example, likely Telus too). Do your research before buying to make sure it fits your use case.
From my POV, the EdgeRouter line gives you more functionality, and UNMS can still give you a simplified overview of things if that's what you're looking for. It's a shame they can't blend the 2 together though.