Best way to spend Allagan Tomestones Of Poetics since Stormblood?

Solution 1:

If you ever have a need for more Grand Company Seals, you can turn in gear bought with Poetics through expert delivery for seals.

Solution 2:

You can turn them into money.

More precisely, you can use them to buy certain crafting components that are very rare and inconvenient to get by other means, and then offer those on the market.

(I can't tell you which ones do best, because the markets are server dependent. Check the vendor to see what you can buy, then check a market board which of those sell for the most.)

Solution 3:

There are a few ways you can convert poetics into cash gil.

The most direct is to go to Idyllshire, speak to the poetics vendor, and under poetics (other) buy the demicrystal item: 25 tomestones each and they vendor for 500 gil.

Alternatively, you can convert poetics into Heavensward end-game crafting materials (the aforementioned demicrystal is one) and try to sell them. Note that the market for these materials is likely shallow, as crafters can skip Heavensward end-game and move into basic stormblood crafting, or buy them with their own poetics, but there are valued glamour items in Heavensward end-game crafts (e.g. the Thavnairian Bustier) so there's some cause for demand.

The next alternative is to buy gear, turn in the gear to the grand company for seals, and then try to convert the seals to gil. A thorough account of your options for that is a question all its own, but I'll note that Grand Companies sell glamour prisms for 200 seals each.