There are a couple of basic types. As Harvey mentioned, they will be electric.
Vertical: The motor will be below decks (right below the windlass or just off to the side). The plus of these to me is that you only have a small hump above deck. The negatives are that the chain has to take a more complicated path to get below, and there is less "fall" (height from when chain comes off gipsy to pile in anchor locker). On some, the motor can be more vulnerable to water/mud/etc.
Horizontal: The motor is above decks, part of the windlass body. The plus is that the chain only goes over a gipsy and down (non-complicated path), and the fact that the gipsy is on deck means that you get something like another 6+" of fall. Probably fewer times you have to "help" the chain. The motor is also not vulnerable to mud, etc. To the bad, you have a larger "lump" on deck, and it can somewhat block the fair lead from roller to deck cleat (there are ways around this though).
There are a few brands, but the Lewmars are common on the 22. There is a V700 (vertical) and a 700 (or maybe it's 700H) which is the horizontal. As an option you can get a wireless remote. The 700 is the most common size on the 22, although they make a slightly smaller one that is partially composite (if I remember correctly) and a little cheaper. The gipsy is on the opposite side on that one.
I haven't completely installed it yet, but I got a Lewmar 700 horizontal for my 22. I'm used to manual windlasses and they had the same horizontal gipsy (chain wheel) arrangement.