I have spent a long time looking for magical systems that promise actual, physical, tangible, undeniable results. I would consider myself a materialist skeptic, so I understand where you're coming from; and like you, it is primarily the aesthetic of magic that attracts me. (Much like I love Catholicism for its ritual and vast body of theological works... but I don't believe a word of it!)
This may help you in your search. I would become a wholehearted devotee of magic if I could just obtain a few simple objective, verifiable results. The following are the systems I have found most promising.
a.) The Ars Goetia and other medieval grimoires: they promise fantastic things, as you are no doubt aware. Imperial Arts, on this very forum, says he's done things like cause an earthquake! Many people don't report any success, though. It might possibly be because Imperial Arts favors a strict by-the-book approach: do what the text says, and don't skip steps... from obtaining a lion-skin to casting the sigils of the demons in the appropriate metals. This is a lot of work, though, and expensive.
Joseph C. Lisiewski has also written a book favoring this method.
b.) Franz Bardon: Bardon wrote an excellent work called
Initiation Into Hermetics, which is basically a step-by-step guide to becoming a hermetic magician, obtaining powers as varied as summoning elementals to controlling a candle flame with your mind. It is very popular and quite comprehensive. However, be aware I don't personally know anyone who was able to achieve physical results with it, except
c.) Prophecy, who is a member of the Veritas Society forums. He's written a less lengthy
companion guide ("A Treatise on Elemental Magic") to Initiation Into Hermetics. It is mostly based on the former work, but with its own flavor. Again, I don't know of anyone who has managed tangible results from following it, but I have hardly interrogated everyone who has tried it, either.
d.) Kobok's Dynamic Psi: another member of Veritas, Kobok is adamant about rigorously controlled experimental psionics. He claims you can learn, through practice, to do things like move quarters, pencils, and even larger objects with your mind. He has written several guides to this effect.
Here is a compendium. As the name suggests, it's more psionics than magic. We get a lot of people claiming minor results from this one, like spinning a "psi wheel", but I do not find that very convincing myself.