I use the Master mainly, however, I do quite like the chaplain.
Right now, I have a master w/ Bolt pistol, combat shield, power weapon and termie honors. However, I do intend to get one w/ 2 lighting claws and combat shield, plus termie honors.
Pros:
Customibilty! I can give this guy EVERYTHING, and not have to worry about wasting stuff. LD 10!!! This means that, with most morale tests (unless swarmed by 20 hormagaunts
) I will pass so easily.
Cons:
Well, he's not that great of a combat monster, the Chaplain, for 101 points is better than a Captain in CC, even if he is a bit more pricey.