We like Jan, who comes down from Wisconsin and sets up to sharpen at Seven Bridges in Woodridge every 4-6 weeks. I won't let anyone else touch Dd's blades anymore.
John at Geppetto's in Downer's Grove, John at Rainbow in Northbrook, and Morris out of the pro shop in the Hoffman Estates park district arena (he may sharpen out of other rinks, never used him so I'm not sure) are some of the sharpeners I know other skaters use. I think it has much to do with who you are used to and maybe that is why people are so loyal to their preferred sharpeners.