Awesome list compiled by reddit user u/Zehnpae. Heres what they had to say about their rankings:

"Scoring as follows:

Front/Back End

4 - Kill 1 dude, grab 1 non-channeled item for front, or no back end.
3 - Typically fast slayers/destroys on a loop or fast kill alls
2 - Large area slayers, slower kill alls, faster animus, small quick channel events
1 - Slower animus, lots of channeled events
0 - Reserved for the hell that is Shadowed Plunge front and Black Asylum back end.

Mid/Boss

3 - No mid event or boss
2 - Has one or other
1 - Has both

Density

4 - Super thick packs, easy mobs to kill, non-stop killing action
3 - Thick, easy mobs but otherwise short dungeon or has empty areas
2 - Acceptable amount but annoying mobs or long empty hallways
1 - Spread out AND annoying mobs
0 - Reserved for Black Asylum

"

Once again all props to reddit user u/Zehnpae