For PVE, that's a fine build for normal dungeons. In fact, that's overkill on the tankiness for normal dungeons That's not a problem as long as you are happy with the way you play.

I like to put it this way:
A basic tank holds boss aggro and doesnt die.
A good tank holds boss aggro, crowd controls mobs, taunts priority mobs that can one shot others, debuffs the boss, buffs the group, blocks, bashes. Interrupts, follows mechanics, and doesnt die.

So if you are happy with how your build lets you do those things, awesome!

If not, here's some ideas.
Ebon Armory - obtained from Crypt of Hearts, this is very close to Plague Doctor for you, plus gives an extra 1k health to the group. (Not as important in 4 man dungeons, but needed in most trial groups)

Torug's Pact - crafted set used with weapons using the Crusher enchantment to further debuff the boss (a good alternative to Alkosh, which requires running trials)

For normal dungeons, I pair Ebon (I used to use Plague Doctor) with some other set that fits how I want to play. I've tried various sets like Livewire, Knightmare, etc, and as long as I have enough magicka and regen (I'm a MagDK) to fuel my crowd control, I'm happy. For reference, on a pure tanking fight, I typically do around 4-6k DPS.


Monster Sets
Monster sets are obtained from Vet Dungeons, the Undaunted Chests or bought for gold or AP from the Golden Vendor in Cyrodiil on weekends.

Since you are experienced with running normals, I'll tailor my suggestions accordingly.

Kragh's - vet Fungal Grotto 1 is really easy to run and should be a breeze with your current set-up, so if you want to dip your tanking toes into vet dungeons, this isnt a terrible starter monster set. It will give you some extra penetration and a little AOE damage.

Grothdarr - vet Vaults of Madness is long, but not hard as long as you follow mechanics. Grothdarr gives you fire damage in a ring around you, which works well if you cluster up the adds via crowd control and then wade in.

Those two are easy to acquire and should help you towards getting some of the others you might want.
I like:
Bloodspawn - good ultimate generation
Lord Warden - buffed resistances in a ring
Mighty Chudan/Pirate - for when you really want resistances
Swarm Mother - if you like range taunting and holding block all the time, this set does good crowd control

But really, go with whatever you like for your playstyle. I wear Grothdarr for Normals and Lord Warden for Vets.


For PVP,
It depends on what you are trying to do as a tank.
If you are learning to PVP, I do like to get more tanky than you would for PVP. I learned to PVP heal by wearing Plague Doctor because the extra health let me live long enough to learn from my mistakes before I died, LOL. Now that I know what I'm doing, I can run around in light armor and feel just as tanky. I did like running Fortified Brass in medium when I was learning to play my stam warden in PVP, but again, I've since swapped to other sets that better fit how I wanted to play.

So for learning, high health and high resistances are good. So is impen trait armor.

But if you want to 1vX or tank large groups, you'll want to look at your sustain, your self-heals, and how you plan on bursting your enemies down. There, you may want to look at sets like Shacklebreaker or 7th Legion, Skoria, or Selene's.

Hope this helps!

No matter what you run for gear, boost your magicka regen. It's very important for heals