Having used both at home, Tomato is much easier for doing standard home WiFi things. You can change wireless power levels, setup guest networks, etc easily within the UI.

Pfsense/opensense is easier when you have complicated routing needs, like multiple vlans with various split tunnels, etc.

It’s not 100% accurate, but imo if you want a short-hand you could say tomato is WiFi focused with routing support, and opensense is routing focused with WiFi support.