The term "nootropic" is very far-reaching. Anything harboring impact upon neurotransmitter improving mental function (and there are a hell of a lot of parameters that define "mental function") could be viewed as "nootropic." Maybe we can narrow down the subject header a bit with specific questions pertaining to them.
As for the "racetam" group of agents; I am unsure where you'd like to take this discussion as a virtual book could be written on them alone, but piracetam's entrance into the industry around the 1960s was the origin of the term "nootropic" so I don't think a discussion could be had without looking into them to some degree. The issue with them is that they all do NOT have the same affinity for different receptors, so despite structural similarity and name, they aren't that alike.
A more prominent one might be leviracetam (the pharmaceutical agent Keppra usually used in patients with seizures), whereas the "SUPPLEMENTAL" ones are always gray market at best, so really hard to put in products when they are being re-classified on a virtual weekly basis ... more recent, they are again black-listed (although you can still find them easily enough ... for now).
Now, that doesn't mean I don't support their use...I think they have placement; but I could write all day on them. What agents were you most impressed with for your "study stack" - maybe its best to start there...