T2 pala and T2 warrior are absolute beautys, T3 warrior is also very cool with Thunderfury and the ally pvp sets for pally/warrior are also a thing of beauty. I also love the epic ally Hunter set and the horde warrior set is veery cool too. I'm a sucker for plate armor but I'm gonna main a huntard :D
I'm biased - Druid T2/T3.
Love the set paired with Jin'do Judgement also.
I loved druid T4-6. Tier 4 is peak Druid for me.
I had some T4/T5 I don't think I ever got T6, only the PvP recolours maybe.
Warrior T3 is unsurpassed by any and all other gear sets of any class in vanilla.
Priest T3 ´´Vestments of Faith´´ for me.
But give a Tauren full T3 and a Thunderfury + Hippo Shield (hippo shield) and warrior T3 is easily the better looking set!
Though I played mage in vanilla I envied the looks of the warlock T1 felheart set
Yeah, the blue glow and skulls etc. look good but still... I can't help but get the feeling that it looks like something the WOTLK team made!
Beastmaster set. My darling, my love.
I think most T1-T3 sets look amazing. It would be easier for me to say which ones I don't particularly like. :P However, Judgement (paladin T2) is probably my favorite despite never playing paladin. It fits class fantasy perfectly - the faceless hand of justice. Druid T1 was also quite interesting and it also fits class fantasy very well.
I think I only don't like paladin T3 and warrior T2. First one's too bland and helmet is out of place, the other is too edgy for me..
It's bolder and simpler than anything from Wrath, with colors that are more saturated without being "brighter". It's just perfection.