I know what your talking about, An electric "chef's choice" knife sharpener, they work really well if your just a chef that wants a sharp knife easily done. In my box of stones and stuff i have a chef's choice model 460 diamond hand hone, it does good for starting and edge at the right angle quickly but needs further touch up on the edge, but the electric ones and if its the 4 stage do a great job but there pricy, id have one but i really dont need it.
All the other methods take abit more time "or alot" I have the lansky's and straight stones and diamond ones and many others to speak of, but you would probly want the chefs choice.