Both are nice quality saddles. I would go with whichever style fit my horse. Pozzi's are wayyy more expensive then Martha Joseys though. Don't know your price range but Pozzi's can go into the $6000+ range. Martha Josey's seem to be $3000 and under, depending on how fancy you get.
I personally think many of the saddles are very similar build wise between these two brands.
If it was me, id go for a Pozzi just because I like the selection that she has. You can get them custom made as well, where as Martha Joseys, im not so sure. Posted via Mobile Device
I always drool over the Pozzi saddles, as they are absolutely gorgeous, but I've never owned one so I can't say. I just tell myself all that sparkle would be way too much extra work to keep clean, versus my simple plain jane Circle Y that I have.
I have heard that both are great saddles. If you're able to go to a tack shop and try both on, get the brand that fits you and your horse the best.