this is a tough one. in a fight, hellboy will prolly destroy etrigan. but from a writers standpoint, i think that etrigan would be a blast to write. first thing that popped into my head when i saw etrigan is that he always rhymes.
DUDE!!! Not fair, Epic pulp hero with funny one liners and an epic gun. Etrigan is one of the coolist comic characters of all time he rimes when he talks (unless he has a bad writer) and he is amazingly fun to read about.
Gone Gone oh form of man and all... such a wicked hard choice.