Petroni gets pretty short shrift around here, doesn't he? I'm surprised - he's more competent than most journeymen SW directors. Maybe it's the lack of zip and exuberance about his movies - they're all fairly stately in their pacing, even Life is Tough... Hallmarks of his literary bent, perhaps.
Anyway, my ratings:
Best: Death Rides a Horse (a stone-cold classic)
Worst: Life is Tough/Sky Full of Stars (though, as others have said, I still like them)
Overrated: Tepepa (see above)
Underrated: Night of the Serpents