Anything with adds is usually pretty hard. I think Baron was middle of the road hard. I found if my tank kept aggro, spammed shield block and used 1 holy water I could take him down without too much trouble. Getting to Baron is a huge PITA as I really hate the abomination gauntlet.

Scholo is pretty much off my list. I really hate all the trash you have to clear before any of the bosses.

The absolute worst though, is the troll boss area in ST. The trash mobs have fear and the stupid ghosts that follow one character make it just not worth the effort. Only 5 man I bailed on before even attempting a boss.

Overall, most classic dungeons have way too much useless trash to clear. If I had to do all these lvl 60 dungeons in PUGs I would have unsubscribed long ago. Don't even get me started on Molten Bore. Spending 1 hour clearing trash per boss is just maddening.