A very personnal choice...
it's almost like asking "What kind of shoes should I buy?". It really depends on what you're doing, where you're doing it, what you need and expect, etc. With all of that in mind, my general favorite for 90% of the time I spend on the water is a SOSpenders auto-inflate with the integral harness. There are other good brands of this basic thing, but any auto-inflater with a harness would likely be the best bet for most people. For me anyway, the choices lined up like this: regular PFD-too hot, bulky and uncomfortable; manual inflatable-much better, but what if I end up in the water either unconcious or otherwise unable to activate it?; autoinflate without a harness-even better, but if I suddenly need to go forward in big water, I have to put on another piece of equipment; and so the decision was made. I have also found that guests aboard the boat are much less likely to complain about having to wear an A-F pfd than a standard, this is doubley true with kids. The only downside (you know there had to be one!) is cost. At an average of $150-$200 a pop, they sure ain't cheap! I carry 4 adult size and one kid size 'hybrid' on the boat, so I'm well aware of this problem, but in the long run I felt it was a worthy expenditure. If they only save one life, they've all been paid for a hundred times over!One last thing to consider, IMHO, is accessories for the jackets. Tucked inside each one (and securely fastened) is a whistle and a strobe light. The adult jackets also have a webbing knife and a single handheld aerial flare. I figure if I'm in the water watching the boat move away, these things just might come in handy! I'm also considering adding a 'rescue streamer' and a 'laser flare' to the jscket inventory, although these would likely only be added when I'm blue water sailing or perhaps singlehanding at night. On a bright summer day on the little lake where I spend most of my time on the water, I can't really see the added weight and bulk for something that would likely be of little use on a small lake full of other boats. (BTW, has anyone tried one of those 'rescue streamers'? What did you think of it?) Anyhow, when you figure up all the money that it costs to own and maintain a boat, spending some serious coin on lifejackets doesn't seem like a bad idea!Jeff