Not sure about the XM319 Rims in the second one holding up
Why not? they’re decent if not trendily wide rims. You don’t say what rims you currently have, but your OP suggests its the spokes and hubs that are knackered not the rims?
Think I’m going to go for Stans Arch mk3
Arch’s are very good rims, but they are quite light, they are strong for the weight but not really at the ‘strong’ end of the spectrum.
So what exactly do you want?
(and what exactly have you currently got rim wise!)
Worth thinking about how have the XT’s become knackered too, because if looked after C+C Shimano hubs can last indefinitely, worn races/cones and bearings are normally due to lack of maintenance so if you go for Shimano again and don’t change your habits you’ll end up in the same situation. If you go for Cartridge hubs and don’t change your habits then you might find you’re regularly replacing bearings in them anyway.
Got a LBS with a decent wheel builder? They might be able to sort you out with some locally built wheels to suit your requirements, can often be cheaper in the long run and a lot of the strength/reliability of wheels is down to the build as much as the components.