Piracetam was mostly ineffective for me, regardless of dose. The only effect I got was enhanced visual contrast. Nothing appreciable cognition-wise, and I was in school at the time studying various subjects.
Pramiracetam did provide me with enhanced focus for the short duration I took it, but it significantly dulled my already introverted personality. I'm also not convinced it's entirely safe to take, especially regularly or in any of the higher doses (e.g. 500mg) that I see people experimenting with. This is the only racetam I've taken that has actually helped me study, essentially allowing me to study for a longer duration before my brain gets fatigued.
Oxiracetam provided essentially no effect for me, regardless of dose. There were times I thought I might be experiencing the speedy/stimulant effect of oxi, but it was so subtle that it could have just been placebo or something else.
I have some aniracetam that I am going to start taking within the next week, but I am not getting my hopes up. After I finish the aniracetam, I don't plan on buying any more racetams.
Noopept did provide me with a noticable but mild anxiolytic effect, but did nothing appreciable for my cognition.