To address the original question:
"What is the best polish/rust protector/finish"
I'd say it all depends on the application. For finish on interior railings, towel bars, knick-nacks, etc. the aforementioned wax finishes seem pretty good and buff up pretty nice. For something more durable, a high quality automotive clearcoat finish is nice (that's my prefered method) and can be found in rattle can quantities for small projects.
For rust protection/finish on outdoor pieces, I'd say stainless steel would be ideal, if a little expensive. Below this, a good heavy multi-component paint system is best. The best system (IMHO) is a zinc based epoxy primer, followed by an epoxy color coat followed by a clear top coat. (This system will run you over $150 from Sherwin Williams as they only sell in gallon quantities).
Below that, I prefer Valspar's oil based enamels (available at Tractor Supply amongst other places). It is also a multi-part system, although it is somewhat limited in premixed colors. The Valspar is also available in everything from rattle cans up through gallon cans.
With any of these it is important to remember to get the steel good and clean either through powered wire brushing, or sandblasting. And also remember that the best way to apply the paint finishes is by air. I have a simple HVLP spray gun that works pretty well for general applications, although I would not want to use it on a custom auto or anything too fancy. While I'm NOT a professional painter, I'm not TOO terrible with a spray gun. I still end up with a few spots that need wet sanded and touched up, but I am getting better. There is definitely a knack to spraying paint
My two pennies worth anyways.
-Aaron @ the SCF