I don't think Mike Mignola is really that underrated, guys. It seems like every other artist who is ever interviewed stops to sing the guy's praises. He may not sell 50,000 copies of HELLBOY when it comes out, but that just makes him "overlooked" at best, but definitely not underrated. Very few people say Mignola sucks.
I'd recommend THE PATH. Just read the trade a couple of weekends ago. Great series. Bart Sears' art definitely steals the show. He draws the book at half-size and then blows it up for the inker to finish off. It's beautiful stuff, done in two-page spreads with a great attention being paid to storytelling and structure.
Ron Marz's story is surprisingly good, for those who might remember him best for his lackluster half of MARVEL VS. DC, or for all those members of H.E.A.T. It's the story of a monk whose brother is killed by the gods, and who then finds himself in possession of one of the gods' weapons, and an outcast in his own land.
My full review comes out tomorrow over at CBR. (I think the link is in my .sig...)
I think all three of the books you mention are worth reading, but I'd probably go with THE PATH because there's more of it coming at a regular schedule.