I know a guy with a Cowboy. I believe he's always had good luck with it.
He also has a Juki 441. I own a cobra 4.
The Juki 441, cobra4, cowboy 4500 are all pretty comparable from what I can tell. I see little variations of each but not one stands out as the better machine from what I can tell. I do think I like the presser feet on the Cobra better for bullet loops and tight spots but it's probably what you get used to.