I've been round the houses on this for a couple of years. The truth is that with decaf you just don't get the flavour complexity and subtlety that you get with regular beans. However there are plent of decent enough options. Currently I'm buying these
https://woodenhillcoffee.co.uk/product/swiss-water-decaf-beans/ - they are decent enough, not too dark and bitter and they seem to behave nicely in my Sage machine albeit with quite a fine grind. I'm also buying these as they are quite local to me so I go and pick up, save postage and support a local business.
I've tried various blends from Decadent decaf, Rave, Grindhouse, Coffee by the Casuals, Extract, Neighbourhood. None were undrinkable at all but none became my friend for life.