Some people will say that you get what you pay for, but experience will show that the most expensive fins in the world are not necessarily going to be the best fins for each one of us. Fins, like shoes, are very personal items of gear. They have to match as closely as possible our feet's three dimensions: length, width and arch height whether we're planning to wear the extra bulk of socks/boots or not, so we're best off trying them on for size before purchase, wearing those extra socks/boots if that is going to be our normal use. It's a veritable odyssey finding fins that fit perfectly, not least because individual models are commonly labelled "Small", "Medium", "Large" and "Extra Large", each of which can mean anything. It's appalling that in this day and age fin makers don't provide exact measurements in millimetres (the Mondopoint system) of each fin pocket size's foot length and foot width, using the specifications of a National Standard such as DIN 7876.
Choosing fins isn't only about getting the right size for your feet but also about the right blade stiffness to suit not only your physical strength and stamina but also your priorities, whether it be power, manoeuvrability or endurance or any combination of these. There is no such thing as a "universal fin" in terms of sizing or performance. And you will find if you read some of the threads in this forum that there is a lack of consensus about the science of fins, which is hardly surprising as people often forget that the word "science" comes from the Latin word for "knowledge", i.e. what we currently know, not an absolute eternal fact or truth. We may understand how finning works better in ten or a hundred years' time. At the moment, there are just too many variables to control before we can reach a conclusion.
Note that I haven't so far made a recommendation of a make or model of fin that will be perfect for you and your wife. I don't intend to do so in this message because it's a distraction, but I will reveal that I use traditional all-rubber full-foot fins when I snorkel (I don't scuba-dive) in the North East of England and I'm very happy with the few fins of this type that I own because they fit my feet exactly, they suit the gentle style of snorkelling I enjoy now I'm in my sixties, and they're relatively cheap compared with the plastic-bladed fins I dislike (fin choice is partly rational (science) and partly irrational (fashion)
). It took me quite a while, and plenty of experimentation, to locate what are my now favourite fins. The fact that my choice of fins suits me is totally irrelevant to you, however. You will have to make your own voyage of discovery when it comes to fins, and if you are in a position to borrow pairs of different types, then you can make up your own minds by testing the fins in the water and seeing whether they do what you want them to do without causing you fatigue or flopping about inefficiently. I recommend that you don't blindly follow anybody's advice which is limited to "Buy Brand X" or, even less helpfully, "Buy Model Y", because you will be on the receiving end of somebody else's choice of fins for themselves, not you. We live in a diverse world where everybody's dimensions, priorities and preferences are different. Don't rush to a solution, particularly somebody else's solution, focus on defining the problem of fin choice more precisely first, from your perspective, not excluding the criterion of cost, of course, but not letting yourself be over-influenced by it.
