Paradoxical reaction to caffeine seems so strongly correlated with ADHD that they should make a test for it.
There has to be some kind of issue regarding dopamine regulation that is related to ADHD.
In the past, many people in my parents generation would self medicate with nicotine and caffeine.
Gwern wrote a good article about caffiene+nicotine's remarkable effectiveness. Properly controlled medication is probably the less harmful option. Prepubescent children should not be taking any stimulant medication at all unless they have extremely severe cases.
Recommended reading on ADHD
My thoughts on specific stimulants:
Dextroamphetamine (Adderall): Terrifyingly effective in therapeutic doses (under 30mg). Problematic to prescribe because basically everyone "benefits" from taking it. I think it's somewhat bad for society if we allowed everyone to take it, because of the high abuse potential but it's too late to control it. Basically everyone in certain high-stakes intellectual fields are taking Adderall including all the world leaders. Fairly clean, in terms of side effects as long as you have a healthy heart. Dextroamphetamine is usually abused through insufflation.
Methamphetamine (Desoxyn): You would think this would have zero therapeutic potential but it does seem to get prescribed as a last resort. Might be useful as a diet drug in very small dosages, but realistically, it will never happen. The greatest generation was hopped up on this when rebuilding after World War II, so it can't be as life ruining as it's made out to be. Street meth is not real. If you take that shit, you WILL die.
Methylphenidate (Concerta, Ritalin): Slightly dirtier than Dextroamphetamine but Concerta has a slightly lower abuse potential because of it's inconvenient time release design. Ritalin is a bit rough for people sensitive to medication and children and it baffles me why instant release is so commonly prescribed to children. Unlike Dextroamphetamine, even low doses can cause depersonalization and SSRI like emotional blunting. This might be a desirable effect for those with emotional regulation issues.
Atomoxetine (Straterra): This shit is nasty. Terrible side effect profile, but prescribed because of low abuse potential. I can't tell you if it works or not. Somehow "not a stimulant" despite having the same side effects as one.
Modafinil and Adrafinil: Somewhat dodgy to get in the United States, as a Schedule IV. Felt sleepy on it, like most stimulants. Allegedly improves ADHD symptoms and is used by people in countries where stimulant medication is illegal. Did not notice much of an effect.
Caffeine+Nicotine+L Theanine: The only effective legal stimulants, synergistic effects. For me, two cigs and a black coffee in the morning calms me down and makes me significantly better at careful tasks that require focus. The L Theanine is just to counter some of the side effects of caffeine. Nicotine just by itself is not as damaging or addictive as society says, but addiction potential is still high. Caffeine also has an addiction potential that should not be underestimated.
Cocaine: For those with moderate ADHD, small amounts of cocaine can make you sleepy and relaxed. Zero self medication potential due to side effects, illegality and abuse potential. Never do this.