I really really love my warden tank. It's based around heals and has insane survivability. I used to love my DK tank but have grown bored of it. I also have a sorc tank which is very fun too. Warden is much more fun than DK imo.
OP ask about easiest tank to use. Everyones reply about who is the best tank...
Yep, and he asked which is easier warden or DK. First comment - best is templar
It's curious what is balance between too short or too big original post. In both cases of extreme people simply don't read.
OP, DK is easier by lot of factors, first of all with DK you may literally permablock in trials which makes everything easier to learn and understand.
I used to main a DK khajit tank back when I was around cp 250. That was before morrowwind, but never had trouble tanking vet dlc hardmodes wearing torugs and ebon (never did get alkosh), cookie cutter alcast type. I turned the khajit into DPS/farmer.
I'm now 810 and recently levelled a very similar argonian build and can't sustain or stay alive. I don't get it. Even changed to ebon and plague doctor, still terrible. It's embarrassing and weird.
When others value another class above the DK, it is because the are appreciating what it can do above and beyond tanking WHILE tanking. This is a valid view. Perhaps somebody can value a class over a DK because of all the stuff it brings while tanking.
But being best at tanking itself remains the purview of dragon knights.
What is your goal? If your goal is to screw around and stick to mostly normal content, go with whatever you like. If you intend to do vet content (including vet trials) you'd be wasting your time not going with a DK. DKs have the best abilities for the job vs. everyone else. When necros come out, they'll probably be BiS off-tank.