The one time I took adderall I didn't feel any different, but there were several points when I was explaining my world domination plans where the guy who gave it to me interjected with "that's the adderall talking". Looking back, the plans were somewhat manic.

Modafinil is for wakefulness more than concentration and combating ADHD. For example, USAF flightcrews use it for long sorties. When you find the right dosage for yourself it can feel a bit like a very strong, prolonged caffeine buzz.