For me it's definetely methylphenidate (Concerta and Ritalin) it just made me anxious while under the effects and had to do something, but one of the worst effects is that it made me autistic and robotic af. I didn't want to talk to anyone during the effect and if I needed to talk it made me socially anxious, felt weird talking to people and also really robotic, one effect that is also really remarkable was that it was imposible to laugh about almost everything, when someone told something funny I just got angry. Due to this side effects was the reason why I switched from Rubifen (Ritalin) to Elvanse (Vyvanse) and it was one of the best decision that I have taken in my life, my life felt so shitty while on methylphenidate, I also use to snort it and was even a little bit addicted to this ADHD drug that my psychiatrist prescribed me.

PS: Elvanse is the opposite of Concerta in terms of socializados, it makes me more social, more talkative and more open to people