As a general rule we recommend:

Spell Speed (to 2.46–2.48) > Critical Hit > Determination >= Direct Hit > More Spell Speed

Previously, Spell Speed was more viable due to the the general potencies being a negligible gain or loss whether the demi-summon phase drifted outside of buffs, but with the addition of Solar Bahamut at Lv. 100, it’s now more important to align with with raid buffs. Spell Speed is also weaker at the beginning of the expansion, as a suitable amount of Spell Speed to make the build remotely viable isn’t possible to get natively. Because of this, Spell Speed builds are not recommended, and generally won’t be recommended throughout the expansion.