I'd say switch from being Resistance + Fighting to Defense: Ice Armor or Shield Defense. Ice is easiest to soft-cap with cheap sets, and instead of always stressing for Fiery Embrace to recharge, you just chill in your ice cube when necessary.
And then go from EM's primarily single-target attacks to AoE: Mace or Fire.
I've had a lot of fun with Shield/Axe, which has decent AoE and (unlike Mace and EM) no stuns, but all knockdown for mitigation.
If we are to die, let us die like men. -- Patrick Cleburne
----------------------------------------------------------
The rule is that they must be loved. --Jayne Fynes-Clinton, Death of an Abandoned Dog
I'd say that the Stone/Fire is a decent changeup. Not only in the primary (Defense + Regen combo until Granite, mainly), but also in the secondary (single-target versus AoE damage). Teleport will round out the changes.
Let me never fall into the vulgar mistake of dreaming that I am persecuted whenever I am contradicted.
~Ralph Waldo Emerson
"I was just the one with the most unsolicited sombrero." - Traegus
Fiery Aura: Resistance based, light on mitigation, accurate taunt aura, active mitigation, heavy offense.
Stone Armor: Defense based, heavy on mitigation, auto-hit taunt aura, passive mitigation, penalizes offense.
That's about as different as it gets.
Energy Melee is harder to find an antipode for. Because of the single target focus in EM, I'd say go with Elec melee to change it up, but you'd still be mostly energy/smashing damage and keep the disorients. Fire melee would be a good one, it has no mitigation (as opposed to EM's stun abundance), it is AoE capable and it does not share a damage type except for a few instances of smashing.
Where to now?
Check out all my guides and fiction pieces on my blog.
The MFing Warshade | The Last Rule of Tanking | The Got Dam Mastermind
Everything Dark Armor | The Softcap
don'T attempt to read tHis mEssaGe, And believe Me, it is not a codE.
Thanks for the thoughtful replies, folks. Clearly I need to go give my Stone/Fire tanker some love.
I admit that I miss the Mud Pots sound effects. 
id never thought id say this but!.....
i agreee with aett *faints* :P
I just finished taking a SD/Fire tanker to 50 and it's a lot of fun. Massive AOE and ST damage output in a package not a lot less durable than Invuln... and considerably tougher than Fire Armor. (Well, I'm sure Severe will disagree but considering the amount of inf he's put into his Fire tanker I think it's still a valid consideration)
Soft capping was easy and cheap... with the right power selections you can get just 3% short of the 45% soft cap with SO's. With a realistic build you'd need to find around 6-7% defense to Melee/Range/AOE to soft cap; a fairly cheap and trivial thing to do with IO bonuses. The ease of soft capping allows you to devote more attention to other bonuses instead of having to focus on defense.
All in all this tanker approaches the damage output of my SO/HO'd Spine/Regen scrapper (older character without IO bonuses) and is just below the durability of my soft capped Inv/Stone tank. It's a long ways from my BS/Shield scrapper's damage output but then it's a TANKER, not a scrapper... it isn't supposed to have that kind of damage.
As was mentioned you may also enjoy playing Stone/Fire; I have one of those at 50 as well. It's pretty squishy in the early going but once you get 32 it's the next best thing to unkillable like all stone tanks. You will need to keep in mind the basic mobility problems of a stone tanker but if you're up for that challenge the character can be extremely good.
In raw survivability there's nothing else in the game that equals a Granite armor tanker so if you want to give it a try Stone/Fire is probably about the best combination to pair with it. Unrivaled durability coupled with top end damage... even with Granite's damage penalty it's still quite respectable. When the Statesman's TF first entered the game in issue 9 I found that even on SO enhancements a Granite/Rooted tanker could tank a tower buffed Lord recluse without assistance.
Anyway, having played both of the above combinations I'd say both are a lot of fun. The Shield/Fire is just pure carnage; it's really a heavy duty scrapper instead of a tanker although there's nothing at all amiss with it's tanking abilities. Stone/Fire can be frustrating with the limited mobility but if you can adapt to that and want supreme durability then that's your pick.
COH has just been murdered by NCSoft. http://www.change.org/petitions/ncso...city-of-heroes
I'm back in the game after a four-year absence and my Fire/EM tanker (originally rolled around I3) has been rocketing through her forties, and will hit 50 in not-too-long. I've got serious alt-itis but I've rolled very few tankers other than my main one. I'm ready to have a less-squishy experience for my next tanker.
I'm looking for ideas on how I can my make new-tank experience as different as possible from the one I've been levelling. I've got a stone/fire tank languishing around level 15 that I can start paying more serious attention to, and I've been futzing with a possible Shield/BA in Mids. One of the compelling things about the stone/fire tank is that I'm likely not going to be in the Leaping & Fighting pools, further differentiating from my fire tank, who has both.
Any suggestions?