Interesting, here are my opinions:
Revered Elder
No other specialists participate in combat, unless both sides have a Revered Elder. Promotable to the Chancellor
Combat priority: 2
Chancellor
All global effects are nullified within the range of 1 standard outpost.
Princess
Increases her outpost's sonar range by 50% of the standard sonar range. If you lose control of your Queen, the closest Princess becomes the new Queen. (The idea here is that the sonar range no longer grows exponentially, meaning it is a lot harder to cover the whole map.)
Spy (promotable from infiltrator)
Local: Drains all the shield charge of any outpost it attacks. (addresses shields stacking and turtling, which the chancellor can't deal with). Global: 'Attacking' specs drain an additional 10 shield in combat.
Combat priority: 4
Sentry
Fires on an enemy sub once every 2 hours while at an outpost. Each shot destroys 5% of drillers rounded up. Sentry's range is half of its outpost's sonar range. Target is chosen to maximize damage. Only 1 sentry can target each sub.
Promotes to: War Hero
War Hero
Destroys 20 enemy drillers when participating in combat. Captures assassins, saboteurs, and double agents before their abilities are applied. Prevents firing from sentries and targeting from pirates.
Combat priority: 7
Intelligence Officer
Adds 25% of standard sonar range to all your outposts' sonar range. Shows you the type of all outposts that are outside your sonar range. (same idea as princess)
Hypnotist
Takes control of all captured specialists present at his outpost, resists being hypnotised by hypnotists.
Promotes to: King
King
Global: Destroys 1 enemy driller for every 3 of your drillers that remain after shield phase in every combat you are involved. All shields reduced by 20, except at king's outpost, where it is increased by 20. All your generators produce 15 less electricity.
Pirate
Sub carrying Pirate can target another sub. When targeting a sub, the Pirate's sub travels 2x faster than ordinary subs, then travels at 4x normal speed to nearest friendly outpost. Promotes to Pirate King.
I also think there need to be more mechanics for subs, and more ways to counter/interact with them, so:
Pirate King (promoted from pirate)
Local: You can target all subs in the standard sonar range of the outpost that the pirate king is positioned at without the need for pirates. Global: All pirates destroy an additional 10 drillers.
Navigator Promotion II (or just another promotion from somewhere else):
Local: You can launch another sub from the sub that this spec is on as if the sub were an outpost. If you have a pirate you can merge drillers with another sub (including gifts), while all specs on the sub merged with are redirected to nearest friendly outpost. Global: Pirates can target own drillers. (this spec opens up a whole lot of tactical possibilities btw, which I think suits this game a lot)