I think the Ally unfriendly specifically ought to be primarily a wizard flavor controller
It is evocative of the classic magic-user, with his space-filling fireball and rebounding lightning bolt.
It's also an unintuitively-good combination with allies who are more or less obliged to melee and/or not that mobile, especially defenders, since it gives the enemy an incentive to engage the party closely rather than skirmishing or hanging back where you get pounded by the wizard's big AEs or blocked by walls or hampered by obscuring zones or the like. (Y'know, in retrospect, the early-4e wizard was maybe designed to work well with Fighters, melee Rogues & melee-capable STR Clerics... a classic iconic D&D party.)
Other pre-E controllers with selective AEs, like the Invoker got smaller AEs & Zones and shaded into secondary leaders. One consequence may have been (I played an evoker once at high heroic, so I'm not speaking from experience) that they work fine with ranged and more mobile melee types, since the above incentive is gone, and they can support fast/aggressive allies who close with the enemy early, especially strikers like Avengers or Rogues, even centering AEs on them when they get mobbed.
...oh, back on something like topic, now that I'm thinking about the subtle differences among extant controllers, the eHunter had a rather poor multi-attack that served few of the purposes of controller AEs, and a single-target condition-infliction at-will & encounter, none of which gave it much control, then it had wildly OP Primal daily 'utilities,' starting with Stalker's Mist (and not really going up much from there, because there's not a lot of up to go from there) that created crazy zones, delivering the real control for the sub-class. So I guess it had a flavor of its own, too. Sadly I know next to nothing about the Psion and it's flavor of control... The Druid, OTOH, was interesting, tougher than other controllers with primal-class hps, and with wildshape adding the flexibility to switch between melee-control beast powers and more traditional controller invocations, that's quite a bit of flexibility. There was also a druid sub-class that did a lot of summoning, and er, made plants grow. ::shrug::
Obviously Martial Controllers should get their own subtle gradations of control, too. The one I recall that was actually completed, the Dreadnought, tended towards melee and close blasts, featuring both standard-issue weapon combat and intimidation-based attacks using, I believe, martial implements. That's a flavor of control. My 'soldier,' (I'm re-incarnating as a Marshal warlord sub-class in 5e discussions, even that name is a step up) from the Martial Controller Underground used Formations of allies & facesless NPC 'troops' to deliver multi-target attacks all around his allies and/or using a formation to volley fire into a beaten zone or the like, and/or could be 'prickly' and zone-controlling like a 3.x tactical build. In between eds, I thought of a (Martial Arts/Fencing) "Master" martial-controller concept. The idea was manipulating enemies in combat, both through guile/intimidation and maneuvering/conditioning - that and being /really/ good at martial practices & providing grandmaster training both like the alternative rewards and as a stalking horse for powers that could be centered on allies. A later version was going to use a pool of dice to attack, and spend hits to inflict damage to multiple targets and expend hits (& misses) to activate various maneuvers.
