First and foremost, what method of transportation will you be taking while wearing the vest, i.e. wading, boating, kayak, etc.
If you are wading, you can get away with a manual inflation vest. If using any type of powered transportation, I would opt for the automatic inflation vest. If kayaking, you probably should get a kayak fisherman's vest (not inflatable). My recommendations are based on possible water splash on the vest and possibility of being unconscious due to an accident (i.e. powered transportation). With a kayak you have the possibility of taking a "dunk" and/or having an accident that renders you unconscious. Just my 2 cents worth.
Above all, use a pfd when on or in the water. . . . .
Try them all on FIRST. They have to be comfortable to wear for hours and hours
Bass pro shops carries all the decent brands. I went and looked and there are a few that have rough edges in the neck area that will bother you etc. I finally tried them all on and found one of the BPS ones that had a soft material in the neck and they fit well so we got that one.. I think they were $149 each...
On my center console, I wear a 32lb buoyancy manual inflatable belt. I went with a belt, as I find them much more comfortable to wear, especially for long periods. I went with manual operation, as I've been know to fall in when messing with outriggers etc, and don't want it inflating in those instances.
The obvious draw back with manual operation is that you need to operate manually. If you are unconscious, then it will do you little good. Being a belt also requires a little more effort to don it, but as long as you are not unconscious that is not a problem.
If the conditions turn bad, I have no hesitation in wearing a regular Type I vest.