You need to get your GLA, minimum to level 22 to get provoke, you wont get far in endgame without it.

Now I recommend leveling both, I did and I don't regret it. Some fights are better suited for PLDs, others for WARs, but both are good tanks. I just focused my first myth buys on the accessories (there were no X Primals at the time) and the belt, all of them are wearable by any tank. And the rest I started as full Darklight Tin Can xD.

By the time I had bought all accessories and belt I had the luck to have gotten Coils Body and Pant, both are wearable by both tanks. Also I bought the head piece for both PLD and WAR as this helmet drops from T5 and is a safe buy.

For feet I went for the PvP Warwolf Soleret of Fending, even if they are meant for PvP, its the only Feet ilvl 70 that can be used with Allagan Pants, and they are better in every aspect than Hoplite/Lords as they have more Vit/Def/M.Def.

So I managed to gear both my tanks pretty much at the same time and the only piece that was job dependant was the head piece. and the only level 70 pieces were feet and hands.

This gear setup will give you an average iLvl of 86, which is more than enough for all content, even T5 if your not main tanking.

Finally Last week I got lucky and both Allagan Feet and Hands droped on me, so I got both my tanks at 90 in a single shot!.

Final Note, get Dual Haken for your War if you want to do coils with it, is more difficult to hit accuracy cap with WAR, and the Dual Haken fix all those problems.