Anchor types: Boaters tend to be opinionated about anchors, but you should regard such opinions - whether praise or scorn - with a healthy dose of skepticism and choose what is right for you.
What anchor should you carry? That depends on what type of bottom you most often expect to plant that anchor in. The truth is, no single anchor is the best in all conditions.Just because an anchor is normally good in a particular bottom is not a guarantee. Sand that is too hard, mud that is too soft, weed that is too thick, or rock that is too smooth can frustrate any anchor.
Stowability can also influence your anchor-selection. The lightweight anchor stows flat, which (along with light weight) accounts for its overwhelming popularity for small craft. The plow and the claw types are both awkward to stow on deck. These two are more often stowed on special bow fittings that carry the flukes outboard. Such fittings also make these anchors easy to deploy and retrieve.
Anchor size: Once you have decided on type, what size do you need? Anchor manufacturers provide convenient size recommendations based on boat length. Unfortunately, anchor loads are far more dependent on weight and windage, so use manufacturer's recommendations as a starting point only. If your boat is heavier than other boats of the same length, or if it has a higher above-the-water profile, you need a larger anchor than the chart recommends. Likewise, if your boating area could be called windy and/or your anchorages are relatively exposed, get a bigger anchor. Be aware that holding power claims are based on ideal anchoring conditions. In ooze or grass or gravel, holding power will be less-often much less. When it comes to holding, there is only one absolute-the larger the anchor of a given type, the more holding power it will deliver. An anchor one or two sizes larger than the chart recommends helps to compensate for real-world bottom conditions. No anchor ever dragged because it was too big.