The K Custom Dark is a more general-purpose cymbal set with a darker, more complex tone that works across multiple genres β it just happens to be excellent for worship.
The K Worship Pack, on the other hand, was specifically designed with worship environments in mind. The crashes have a quicker attack and shorter sustain to avoid washing out quieter songs, and the overall set is voiced to sit underneath vocals, keys, and guitars rather than compete with them.
My verdict: K Worship if you're playing exclusively in a worship context. K Custom Dark if you want flexibility for jazz, studio work, or other genres too.