Death Knights are insance currently :/
My thoughts are different ragarding warriors and 3.1 -> 3.x:
(1) "Warriors being nerfed in PvE". I assume that is due to the 10% TG penalty. The reason Blizz are doing this is because warriors were scaling insanely well with the new gear. Blizz are happy for warriors to sit just below the pure dps classes (mage, hunter, rogue, etc) on damage meters and in their 3.1 testing they were too high. With good gear and skill you will find that pve fury warriors will be near the top.
(2) "Warriors suck in PvP" That is true for now. We are kited around to our death but Blizzard are addressing these issues and I think that 3.1 will be VERY interesting for warriors in PvP. Blizzard are also on the record as saying that some of the changes are conservative as they don't want to over-buff warriors and have to nerf them later. What they will rather do is check the impact of 3.1 and hotfix/add additional improvements later. Some of the improvements they have said are in the works (post 3.1) are:
* Remove stance penalties (hmmm ... imaging pvp'ing in prot gear with damage penalty ... or pvping in fury without taking extra damage)
* Increase damage on some core abilities (additional boost to over-power being considered).
* Removal of stances - i.e. like DK presences
Btw - lets look at what 3.1 is giving us for PvP:
* Reduction in stance penalties
* Reduction in rage lost when stance dancing
* Rage when hitting shielded target (think this one is on PTR)
* In-combat charge for Arms
* Increased damage of over-power plus able to reduce damage if over-powering a caster whilst they cast (then you would switch to zerker to pummel of course)
* New ability to shatter a paladin's bubble or mage's iceblock
* Weapon mastery in Arms so need to for weapon chain (yes pvp-fury would need to put one on their OH :/)
* Armor penetration bonus in Arms, which could become quite big
Whilst these changes aren't earth shattering what it does show is that Blizzard are addressing the issues of the most under-represented class in competitive arena.
DKs don't scare me in arenas but mages and hunters do *cry* - perhaps a rogue as well as they can perma cc you whilst they nuke your healer. Having said that you will find that an equally skilled and geared DK will beat a warrior in just about any situation at the moment. Luckily the skilled DKs are few and far between

Generally I win most 1v1 fights against DKs but it means using ALL my warrior abilities (i.e. stance dancing a lot)
Furthermore you need to look to the future - it is clear that DKs will go through a cycle of nerfs until the class is normalised ... whilst warriors will go through a cycle of buffing.
So roll the class that you like to play - if you have time roll both and switch to the FOTM (Flavor of the Month) when you want to feel over-powered
