I am not too keen on keys that are only good for one nipple size except for wheel building from scratch with identical nipples, they are a bit of a pain in most other circumstances.
For general purpose I think the
Fat spanner is the bee's knee. It caters for 4 sizes, is not made of cheese (which many cheapies are and therefore the perfect tool for ruining nipples), and (like the spokey pro) grabs the nipple on all 4 sides - an important feature in my (and others who are more experienced than I) view for slip-free operation even for nipples in less than perfect condition or in rubbish material.