I got a lot of relief from Modafinil, and I think its the best drug for ADHD. Any stimulant will develop a tolerance. Its just a fact of life. I've had good results mixing Modalert and Pseudoephedrine. Pseudoephedrine is cheap, and effective. The molecule contains a portion of the amphetamine structure. If you choose to go the drug route. Caffeine also works wonders, but I personally find in my middle age I can't tolerate large doses anymore (I get acid reflux and anxiety at moderate doses).
But, now I have to give you the hard truth. Drugs can help you in the short term, but they're no cure, and they put the wrong idea in your head-- that drugs can fix you.
You have to take control of your mind. You can look for relief from drugs but largely that will result in an addiction to stimulants. I think the only viable treatment is self discipline and meditation and that won't be perfect. Please feel free to discount this, but I believe our minds have an "interior" which can be explored.