As a general rule we recommend:

SpS to 2.46-2.48 > Crit > Det >= DH > More SpS

There is an alternative way to play the job that focuses on maximizing SpS and minimizing Crit instead, which would use this priority:

SpS > Det >= DH > Crit

In general, the Crit set appears better for most situations. Spell speed as a stat excels when it can be fine-tuned around a fight’s timeline, but you can choose to use the SpS set blindly if you wish.