The Fame Monster, one I listen to most. Every track is strong, think it is down to the amount of tracks if you reduced the other albums they would be just as strong. Not every song is my cup of tea on a more track album but this is the same for any album any artist. You are not going to like every track. There are some very strong tracks on each album though, and I feel ARTPOP track itself could of come from The Fame Monster it is just perfect. All just my opinions
I cannot choose because:
The Fame: Made me smile
The Fame Monster: Made me feel Empowered
Born This Way: Made me believe in myself
ARTPOP: Made me believe that I am capable of anything I choose to do or be !
The Fame Monster is the best, but it unfairly benefits from it's shortened track length. If you cut ARTPOP or Born This Way down to 8 songs, they are both contenders.