I've snorkelled since the 1960s and I've never been tempted to switch from traditional natural rubber fins to the thermoplastic concoctions which western diving equipment manufacturers tend to produce nowadays. I own a pair of Gull Hard Mew fins and they are excellent. I have no hesitation in recommending them. I understand that they are the fins of preference for many New Zealand underwater hockey players too. Japanese diving equipment manufacturer Gull's range of fin colours is impressive and their all-rubber full-foot fins can be worn with or without booties.
Gull's website is worth a visit.