I think the word is Holy Trinity ? Where a Tank, Healer and Damage dealers are needed to form a successful group.
Like how WoW does it. How Guild Wars 2 doesnt do it.

I miss the dungeons in WoW, because I am not too keen on the whole 'every man for himself' in GW2's style.

My question is, does anyone know which other MMO is most similar to WoW's dungeon experience that I could give a try?