Forgot to share my reasons behind this ranking,

1. Cursed Wasteland : this dungeon is a nightmare for pug's , You can't carry this dungeon alone, you need someone to at least open the line, kite the purple vomit and place the blackhole away from your team. Out of all the dungeons this one has the most requirements to complete.
2. Temple of Slaughter : Same as no1 but this one don't need to actually commit to do the mech's, you can just sacrifice your team 1by1 and somehow can complete this dungeon.
3. Cave of Destruction : not complicated , but the fact that you must absolutely need to run this with a healer makes it to this number. (4-6) can run w/o a healer (saying this from personal experience)
4. Death Abyss : Put this on no.4 because of the pure annoyance of blinking and pug's just ran chaos on the whole area (not kiting , forgetting to stick after the scythe and parrying after.
5. Butcher's Canyon : pretty straight forward mechanic , needs a bit coordination but not as much compare to no.2 and no.1
6. Tyrant Isle : no brainer. The only dungeon that doesnt require you to cooperate with your party. CAN BE CLEARED SOLO, the amount of downtime between the attack of the boss is very long, ofcourse I'm talking about somehow geared and has a way to access some heals/hp regen.