Phenylpiracetam to me is an obviously dopaminergic stimulant, and the only racetam with effects that are not "subtle" (ie, borderline, if not entirely, placebo). I'd say it's actually comparable to modafinil in some ways, although it is shorter lasting, and the stimulation is more "forced", with peripheral effects such as increased heart rate, sweating, body temperature, etc, rather than modafinil's quite clean stimulation. Tolerance increases very rapidly also, you would not be able to use this every day... although if you did choose to, in my experience, the usual crash that would occur with rapid discontinuation of a stimulant does not generally happen with Phenylpiracetam.
I have pretty mixed feelings about the other racetams, I don't believe them to be entirely placebo and there was a time when I first started using them that I thought they were basically miracle substances, but since then I've never been able to replicate my earlier good experiences.
Aniracetam for me was not really nootropic in the sense that it made me smarter, but at one point in my life it did significantly reduce social anxiety, but was very short lasting (only 2-3 hours) which meant frequent redosing was needed. Also in my experience after taking Aniracetam consistently for a few days, it seriously disrupted my sleep, I could get to sleep OK but would wake up after a few hours, then after maybe 4-5 hours of bad, interrupted sleep I just could not sleep anymore and was paradoxically both very awake but also sleep deprived... a few days of this and any nootropic benefits were unnoticeable compared to the effects of sleep deprivation. Piracetam did this to me too, but Aniracetam was especially bad for it.