Is the (Shadow)Priest the better Mage in WOW?

[Malakar]

I see their point, however: If the "Uber Minions" (Infernal, Doomguard) shall be limited in their usage because of their extreme power, then the Warlock's "best" standard minion - the Felhunter - should combine the "best of both worlds" of the Voidwalker and the Succubus in a satisfying fashion, which is unfortunately not yet the case.

I think the intention of the felhunter is simply to be an anti-spellcaster summon, serving a unique purpose like the other summons. It seems it's Blizzard's intention for all of the summons to remain useful throughout the game, and I think they did a good job of that in my limited experience.