IMHO, any the "unimproved" traditional breeds i.e. those not full of American and Canadian genetics to allow them to compete with continental breeds, will produce the most fabulous beef from low inputs. So just pick one that floats your boat for whatever reason.
We wanted a rare and Scottish breed, so it was the Shetland for us. But if you love the rich red and the beautiful white face of the traditional Hereford, go for that. If that white band does it for you, go for the Beltie.
Rare breeds are a "thing" of mine so I'd recommend a rare breed because they need your help to survive - and the day of low input cattle is coming again.