FAF and LOUD play very differently, so that will come down to what kind of balance you prefer.
It's worth noting that faf does provide coop for all the campaign missions + some custom ones. No set-up is needed: one of you will just open the FAF client, go to the coop tab, and pick the mission you want to run, this will download the needed files and open the lobby that the other will then be able to join (pick a password if you don't want other people to join).
Talking about AI, FAF ships with the now-abandoned Sorian ai: I'd recommend at the very least trying out the Uveso AI from the vault that is actively being worked on and is the basis for several other AIs.
For what concerns UI mods, have a look at Blackheart's guide to UI mods; the vault also has tons of mods that add more buildings and units, not to mention a whole new faction (nomads).
Depending on the kind of coop experience you are looking for, there are also dedicated maps with survival-style gameplay. Try to be more specific about the kind of games you enjoy playing so I (or someone else) can give better suggestions.