I'm talking about all those named rare mobs and this is going one way:
Please make them tougher than random rare (yellow) mobs and give them the same -maybe better- benefits (loot and NV stack).
It makes sense just like it makes sense for legendary items to be better than rares ;)
I really like the idea of those mobs, already liked it in WoW, but there they are of much more interest somehow (be it a special pet skin or just guaranteed loot, in some addon they were rather tough, too). Enough WoW.
I have some ideas for three skeletons that I meet rather regularly in the Keep Depths. I don't know their names, but their flavor texts, they are:
"Leader of the Skeletal Guard":
How come this guy walks solo and drops like a trash mob? I'd like him to be a commander in shiney armor with a lot of minions of all weapon types: archers, axe-wielders, s'n'b-guys.
"Former Leader of the Skeletal Guard":
Well, there could be an explanation for him walking alone, but I'd rather think of him as an elite, not yet rusty combatant with his elite bodyguards still loyal to him. Maybe a strong purple guy and 2-3 champion minions.
"Heads will roll":
Seriously, this executioner could rock. I think of him like the Butcher in classic Diablo. I'd like him to be tall like the last survivor of an -imgainary- six-man Avenger champion grp (on a side note: please give that affix some love, it's totally offset by the disappearance of a champion alone).
He wouldn't have minions and he wouldn't need them. I know this could lead to a one-shot-scenario which is generally not wanted, but this could work, it'd be reasonable for that guy. Just needs some tuning and be beatable by melees, too. Maybe a big attack, that you can outrun in time.
So, these are just a few thoughts and I know there are many, many of those rare mobs, which would result in a lot of design work, but I'd appreciate that, it would lead to me actually being excited when I meet one of those.
While you're at it, you could revamp the attached achievement. The "kill 'em all" would need a reset. In an effort to not offend anyone the current "Unique Collection" with it's current status could be rephrased to "meet them all" and a new one could be implemented that requires kills.
The main difference between purple monsters and elites at 5 stacks is that generic purple monsters (not quest monsters) will drop a lot of garunteed magical items where as elites will drop a garunteed rare and some garunteed magicals.
At low MF you will find that these magicals mostly remain magical. Once you get to paragon 60 or have over 200% MF (excluding stacks) you will find that many of these magicals will be spawning as rares.
At MP10 with maximum magic find (300%) and maximum stacks you will probably see purple monsters dropping 6-8 rares often.