My Big decision...AF2, Darklight, Relic, oh my...

[Sapphidia]

You can always do what I did, which I see a few of the other raiding tanks doing (mostly due to hating the Darklight Chest but also wanting to save 1300 philo tomes).

There's no point getting the HQ Darksteel i70 chest because it's the same design as the Darklight Chest! The combo chest/head tincan. You'll be much happier aiming for separate Allagan or AF2 chest/head parts. Also, half the point of the crafted i70 gear is that it's only better than AF2 if you put 5 melds in it... and the tank set is combined head/chest so you only get 5 melds between two equipment slots. Save your money.

What you can do though is make the AF2 Helmet your FIRST buy. As people have said, it drops off Turn 5 so you wont risk having wasted those tomes. It wont be replaced by allagan. Then, use either the Hoplite Chest if you're lucky enough to have it, or if not, you can actually have a BETTER chest by buying a HQ Militia Cuirass (the crafted i55 chest) and melding it with materia, probably crit + determination. HQ Militia Cuirass + AF2 helm is a BETTER stat combo than Darklight Chest as you get pretty much identical def/vit/sta, but get much higher secondary stats, especially threat-wise. The HQ militia cuirass goes for about 20k on my server, and materia costs might vary. You can get away with grade 2 but ideally grade 3 at least for the first two green slots.

You can always swap in the Hoplite chest if you find you need more accuracy - this is the main reason i bought a melded HQ Cuirass, the Accuracy on my hoplite chest was wasted as I was miles overcap, so the parry+crit i got out of the Militia was a substantial upgrade.

My recommendation? Get the AF2 head with Myth, the Darklight legboot combo with Philo, and use either Hoplite or HQ Militia for chest. Save 900 for the Bravura +1 next, and make sure all your other jewellery slots are Darklight (with hoplite ring). Once you've got your relic and +1'd it, replace your Hoplite Ring with the Heros Ring for Myth tomes, and spend your remaining Myth tomes on either gloves/legs/boots/chest depending on which parts drop for you in Coil.

I'd probably aim for the Bravura +1 after the Head to be honest -> the allagan axe drops off turn 5 too. Getting +1 relic and AF2 head and the rest of your slots being Darklight guarantees you wont waste any of your first myth on stuff which could drop.