I don't really think any band with a lengthy career of 10+ album would fulfill that standard (outside The Beatles). Sparks come close in a sense that every Sparks song in the 70's is good and every Sparks song of the 00's is good. However the 80's and 00's I can't say that
If we are speaking about consistent. I guess artist with only one official release album that is pretty good like Jeff Buckley or Dennis Wilson is the only real contender.