Tank specs in PvP

I've always like to be hard to take down in PvP. Classes or specs that make me a glass canon aren't for me. Knowing that, I made some research about Blood DK / Prot Pally / Prot Warrior in PvP but it hasn't respond to my questions.

I know that WOTLK might be the best expansion for them in PvP but I wonder if they really have utility and if it's enough to make them 'viable'.

Which one between Blood DK / Prot Pally / Prot Warrior really have his place in arena and rated BG? better in 2s, 3s, 5s?

What else you'd recommand me to play if I like to be 'hard to take down'?

thanks

Prot warriors are the most viable out of these tank specs but it's not because they're hard to kill, it's all about their burst, mobility and CC. You will be really squishy against casters since you require a lot of PvE gear to make your damage worthwhile. You survive by shutting down the enemy damage, not taking it.

Prot Paladins and Blood DKs suffer from extreme lack of mobility which makes them easy to kite and thus very easy to kill for anything that isn't a paraplegic, especially since both of these specs rely on hitting their target in order to heal.

If you like being an unkillable wall in PvP, you're playing the wrong expansion. The only real way to do it in Wotlk is to play a healer.

Prot warr and prot paly are both viable in PvP.
In Arena Prot warr should be played together with hpaly and prot paly together with rshami.
Both setups have the potential to reach +2,2k in 2s.

As prot warr u want to get 100% arp and t10 two set bonus of prot and fury.
As prot paly u want to get as much strength as possible and t10 two set bonus of prot.

In such gear u are not really a tank because u have hardly any resilience and that makes u more squishy against range opponents than most other specs.