Single-speed winches are the least expensive option but don’t offer as much mechanical advantage as a two- or three-speed winch. On a cruising boat, you’ll most likely find these used for halyards and possibly the mainsheet. If you’re replacing a single-speed winch, consider a geared one that ratchets so you can turn the handle in either direction.
For sheeting in the headsail, you’ll want a two-speed or possibly a three-speed winch. Two-speed winches have a 5-to-1- or 6-to-1-ratio high speed, which is usually counterclockwise, to bring in the sheet quickly, and then turn the other way for a 1-to-1 gear ratio to complete the trimming.