Exactly this. There are a ton of comps that work fantastic but most of the best ones aren't built around the notion of tanking / healing / dps but rather on how the classes interact with each other. As an example, double occultist / bounty hunter / grave robber works exceptionally well with both the hunter and robber exploiting occultist ability to mark and their excellent stun, while getting damage buffs against the marked/stunned targets, while offering excellent healing.
I am really liking the new Flagellant class as well.. obviously being so bleed dependent does not make it right for every dungeon, but in some dungeons they are truly awesome.
Pretty much my pecking order would look something like:
Top tier
- Occultist
- Plague weaver
- Hellion
Mid tier
- Highwayman
- Crusader
- Grave Robber
- Vestal
Situational
-Abomination
-Flagellant
Everything else