My favourite is the Leathergraft comfy suede strap. I have loads of these and they live up to the name.
GuitarGuitar have them in four colours: https://www.guitarguitar.co.uk/search/?Query=Leathergraft+comfy
Also get some strap blocks to go with it - little rubbery thingies that prevent the strap from coming off at the worst possible time
Several companies make them, but GuitarGuitar sell Ernie Ball ones in eight different colours: https://www.guitarguitar.co.uk/search/?Query=strap+blocks