I have a modern small Craftsman 5.5" and an old 7" Craftsman. Night and day difference, the modern small units (they all seem the same) are only useful for the smallest things. The old one I have is okay and I use it. Having used large commercial units, a jointer is one of those tools that bigger is better applies. Not necessarily wider, but heavier. It takes a lot of down and forward pressure to use one effectively with a board of any size. Also they need to be lower than most power tools. I find a large hand plane combined with proper vices and bench much more useful.
if you go with a small bench top unit get the heaviest one, mount it to a rock solid, immobile bench that is lower than normal, so that you can maintain the downward pressure necessary.