Which Versatile Defender?
I'll add one more to the mix: Traps/Ice
At level 50 I solo mine at +2/8 - very nasty. I am currently working on a guide for it. In short it offers:
- Blaster level AoE in Ice Storm that also slows so it lets you use Caltrops AND keep things from running away from Acid Mortar
- Two holds to help against those really annoying mobs
- Some pretty good ST damage in the trifecta of ice attacks
- Easily capped defense across the board
- Mex protection (except sleep)
My favorite moment was joining a farm with a scrapper. It was just the two of us and he commented on how I was doing more damage than him
Current:
Fridgerato - Traps/Ice (Frdm)
Gadgetron - Grav/TA (Lbrty)
Ice/Kin Guide
While I like both Dark/ and /Dark, I really don't think that putting them together is the best idea: there's too much overlap (particularly with THDebuff and Healing). Dark Miasma goes much better with Ice (AoE damage and controls) or Sonic (which, being the ST king for defenders, goes well with everything), or maybe even DP (to capitalise on the insane amounts of AoE -dam), while Dark Blast goes much better with a set like Traps, Storm or Cold, which lack a self heal, and can take more advantage of the debuffs (as well as all 3 liking the immobilise of TT). Storm in particular has great synergy with Dark Pit and Thunderclap giving you a Mag 4 AoE stun (thats enough to lockdown anything shy of an EB...)
1 more vote for traps. In addition to everything already mentioned, you get status protection in FFG and an immoblize. The immoblize is going to be valuable when you're slowly beating down a boss and he decides to starts running... and they most certainly will run.
Secondaries are not all that different... I'd pick the one you find entertaining.
I gotta make pain. I gotta make things right. I gotta stop what's comin'. 'Least I gotta try.