I can think of many bands with predominantly great back catologues but one or two average/quite-good entries but the following are bands for whom all albums I would rate at an 8/10 or above
Bands with 3 or more records as I found plenty with 2 or less albums....
Explosions in the Sky (the debut and the last one scraping an 8)
Simon & Garfunkel
Sunny Day Real Estate
Low (just about)
Cocteau Twins (just about...maybe)