WAR in Defiance or Deliverance is a pretty crazy MT. It's current CD suite is: Rampart, Vengeance, Thrill + Convo, Raw Intuition, and Holmgang. The amount on it's own isn't necessarily as important, but the fact that WAR has access to 2 90s CDs that both last 20s, 2 120s CDs, and the shortest recast immunity ability at 180s. It is, without a doubt, the most long-term durable tank especially in a solo tank situation. However it's biggest falling is that once it's put in the OT position it can do nothing to help the MT in terms of mitigation. Meanwhile, if we take a look at PLD/PLD it doesn't matter which one's MT or which one's OT - they both can offer Intervention and Cover to the other. On top of that they both provide group utility in Passage of Arms and Divine Veil. PLD/DRK similarly can help eachother, DRK offering BN and PLD offering all the stuff I just mentioned.
In a solo tank situation I'd say WAR is probably the best as it has the biggest mitigation suite and has extremely strong AOE damage. In a duo tank situation that required lots of swapping PLD/PLD or PLD/DRK would be better suited. In a situation ala A1S I'd say WAR/PLD is probably strongest, though there can be an argument made for WAR/DRK.
The safest bet to hitch on, imo, is either WAR/PLD or PLD/PLD - specifically for prog, once stuff is fully figured out it'll probably just come down to which is the highest DPS full stop which will likely be WAR/PLD or PLD/PLD, ironically (unless SAM/NIN aren't meta for speedkills, though I can't see that being possible lol).
Anyway all that aside, WAR is slightly more fun as MT now since they gave us a new CD to work with. Not much has realistically changed, though, as you still want to be in Deliverance 24/7. If you're an advocate of actually being in Defiance then IBs are always fun to time and I wish they were more relevant to the meta as I vastly prefer them over FC, but ah well.