I'd only ever played 5 and this was because of it being on games pass after I bought a couple of Xbox for us, coming from a PS4, so will have a crack at Primal in my own time when we're not playing together.
New Dawn is keeping us entertained for a few hours and looks like we'll play it to completion. Far Cry 6 though. Meh. Overly complicated when we just want something to settle into without too much faff and patience.
Totally get it mate. Me and the girlfriend coop a lot. Really enjoyed the Gears of War games, Ghost Recon Wildlands and Breakpoint were fantastic. If it's not on Gamepass you'll find a couple of cheap copies of some gems in CEX. Picked up the entire Borderlands series and DLCs for 25 quid on sale. Best coop fun we've had. Borderlands 2 and the DLC is absolutely brilliant.
If you're new to XBox you should be a able to get a free month of Ubisoft+ for you both on each console. Ghost Recon games are on there as well as a few others.
There's a lot of couch coop and online in the 360 catalogue as well that have FPS and HDR boost. Splinter Cell Blacklist has some absolutely amazing coop and is 3 quid a copy in CEX. Looks current gen but was made over a decade ago