I have the Vixskin Goodfella, Mustang, Johnny, Buck and Outlaw
and the O2 Max.
Vixskin is MUCH more lifelike and I prefer it hands-down. I might buy even more Vixskin toys (!) but I don't expect to buy any more O2, unless they improve significantly. That being said, we do use the Max sometimes and it's a quality, user-friendly, durable toy. It has brought us some pleasure. But IMO, Vixskin is superior.