If you enjoy (or have the time) doing lvl53+ quests, some of the quests do reward decent tank armor. My personal favorite items:
1. Kerra 59 Starshimmer Bracers
DUR: 75 STA: 15 AGI: 15 HPMax: 110 AC: 237 LR: 15
(UBER bracers, but the previous Kerra quest rewards were merchant fodder imo)
2. Lavastorm 53 Magmanite Shield
DUR: 60 STA: 30 HPMax: 75 AC: 454 FR: 20
This shield rocked for a long time until I used lavasteel shield and won a Lava Rock shield.
The Arios 55 War Torn Gauntlets and Arios 57 War Torn Greaves
were okay. I havent completed the arios 59 so I don't know its reward (unless I look it up)