The bay is a relatively forgiving area to anchor and generally pretty easy to set an anchor - so that part is good for you. It's also shallower in most anchoring spots, so that is good, as well as it isn't overly weedy in most spots. As far what size, that brings us back to what Seasick mentioned - there isn't an easy answer... and also no "one best" answer. Variables such as how much chain you want to use and do you have an anchor roller (or even just a bow roller) come into play in picking your anchor. A fluke style is the most common for a smaller boat. A plow works very well, but becomes cumbersome without at least an anchor roller.
Take a look at what Seasick linked and let us know what type of hardware you have at the bow, along with how much chain you'd like to deal with - knowing that, generally, the more the better.
Also "size" can be talked about in terms of actual size or, instead, weight. Both of these will depend on the brand/style you choose. For example, there re probably easily a half dozen brands of fluke styles, if not more. Some manufacturer's ID them in their weigh (lbs), others give arbitrary numbers to them.