Billy Zane: Etrigan did not get as many lines as Jason in the episode but Billy just does a typical generic 'demon-y' voice. Maybe given a second chance and using a variation of his Ansem voice, he'd work a lot better.
Michael T Weiss: A very cool voice. A bit of a cockney accent plus a suitable deep voice. Michael really fit Etrigan's angry nature but I like he had a bit of a Wolverine type of personality. I will say I'm a bit disappointed that Michael didn't get to rhyme but I guess that's more nitpicking. A good example of not only Michael but Justice League's voice work.
Kevin Conroy: Kevin was a decent stand in but I would have liked to see how Kevin could have handled Etrigan with more dialog and being able to do his own thing.
Dee Bradley Baker: This is Etrigan's first TV apearrence where he speaks in full rhyme and Dee deliveries them very well without it coming off as silly or hard to take seriously. Dee gave a nice monstrous voice and unlike the other voices mentioned he does it with a higher voice which surprisingly fits Etrigan very well. Another stand out of both Dee and Brave and the Bold's voice work.
Christopher S. Field: Chris also gets to take a crack at Etrigan's rhyming and does it decently. Chris' voice sometimes came off as unnatural and his performance could be too over the top and while Dee could make a higher voice for Etrigan work I think Chris is a bit too high.
Overall I like Dee and Michael the most but the others aren't bad.