In the case of mask and fins, the primary criterion is a good fit, otherwise the mask will leak and the fins will either cramp your feet or come loose. There is no substitute for trying gear on first, preferably in a swimming pool or open water. Everybody's face and foot dimensions are different, so there's really no point in settling on a particular brand or model of fin or mask before sorting out the fitting problem.
Scuba divers and free divers tend to recommend open-heel fins and full-foot long-bladed fins respectively to snorkellers. In other words, they assume that snorkellers really want to graduate to scuba diving or free-diving. Well, as you say, you are vacation snorkellers, not wannabee scuba or free divers, so go with the fins that are comfortable to wear and to use. I'm a life-long snorkeller who has never really wanted to scuba or free dive and I use standard-bladed full-foot fins and an oval mask when I snorkel off the North East coast of England. When I snorkelled once at the La Jolla Cove in California, I observed how every kind of fin was being used - long free-diving ones, open-heeled ones, bodyboarding ones, pastic-bladed ones, all-rubber ones. The beauty of snorkelling is that you can enjoy the activity with virtually any kind of gear.
So my advice is - don't let anybody tell you that if you're planning to snorkel you must be harbouring a secret ambition to do something "more challenging", so you need some kind of specialised equipment. Snorkelling itself is enough of a lifelong pleasure. Don't decide on particular brands until you find out how well the fins and mask fit you, not somebody else. If at all possible, try out any gear before you buy. When you get to your snorkelling location, see what other snorkellers are using for those conditions.
As for the snorkel itself, just go for a simple "J" type one. Getting geared up for snorkelling doesn't have to be an expensive or a daunting business, but remember you are in the driving seat. Dive store operators are more used to equipping scuba divers than snorkellers and may try to push the high-end gear you don't need at this stage.