EPCQ and EPCQ-L are discontinued (notification 02/14/2018)

most other vendors offer the EPCQ-L equivalents (1.8v Qspi flash) in several packages, sometime 5! (ISSI, Micron, ...): SOP16, FGBA24, WSON, etc...

So I think using SOIC/SOP package for testing is ok, then you can pick (or not) another package for production.

But then you still have to pick "random" parts and test them. And at least Micron part is not easy to find in SOP package.

So we should get at least some guidance from Altera !