1) I like centrophenoxine, it has nootropic effects of it own in addition to providing a source of choline. Citicoline is just much more readily absorbed choline, I believe. So it's a great choline source but I'd probably prefer centrophenoxine. But I haven't had centrophenoxine in many years and I only had citilone recently. Centro used to be a part of my stack, when I had a stack.
2) I haven't tried a lot of them but honestly piracetam is a nice nootropic, I like it, it's my go-to because it's more well-studied and it works. But I find noopept to be about as good a nootropic as there is. It is slightly stimulating, and works very well to increase word recall, multitasking ability, speech and general quickness and ease of though. I like to snort it, though sublingual is better for your nose. But snorted it's way more effective, 10-15mg is a really nice boost and a great morning starter. Damn, I haven't had it in years, I think I'm gonna buy some.
3) Honestly I can't pinpoint an exact duration for most nootropics. The effects are very subtle, it's not like "oh man I came down". It's not the kind of effect you really notice that much unless you look for it, or look back and realize how easy it was to just solve a problem or get work done or whatever.
4) I have some suggestions. There are so many possibilities. First I'll say, galantamine is cool for increased dream recall but it does mess with my sleep, basically it makes me sleep so lightly that I sort of wake up a lot all night, which is the sort of sleep where I have the most vivid dreams by far. But I feel less well-rested, I think it must mess with your sleep cycle. I can't recommend a daily use of it. I have experience with ALCAR and found it nice. I can't remember specifically what effects it had, as it's been like 12 years since I have taken any. Honestly most of these ride the line of placebo, they have the kinds of effects that may be very noticeable if you're suffering from serious brain fog or something, but that are generally very subtle and extremely background. The ampakines are more drug-like than most things classed as nootropics. Sunifiram is a stimulant, moreso than phenylpiracetam. I don't think it's really very good for you.
I take L-theanine every day. L-theanine is an amino acid and completely safe to take, in fact some studies have shown it to demonstrate protective effects on the liver, specifically preventing some of the damage from acetaldehyde (alcohol's toxic metabolite which is responsible for most of its toxicity). It is used by the body as a precursor to GABA and dopamine. It is a safe relaxation aid, it helps you relax and sleep (but it doesn't make you tired), and it has a positive effect on mood. I find its effects more pronounced than most other supplements. It's a staple in my supplement supply.
Medicinal mushrooms - I get a powdered blend of 10 medicinal mushrooms fro my local food co-op, I can't remember all of them but they include Lion's Mane, Cordyceps sinesis, Turkey Tail, Reishi, and others. Some of these (like I think Turkey Tail) have demonstrated in research to shrink cancer tumors. Lion's Mane is very good at regenerating nerve cells. The benefits of medicinal mushrooms are quite amazing, really. I take 1 tsp of this mix once or twice a day. It is quite noticeable. I consider it probably the most important thing I consume.
Selank - there are more and less bioavailable forms, the best absorber is N-acetyl selank amidate (NA selank amidate), though it is less researched so it's probably safer to go with regular selank. Selank is a Russian-developed peptide, a complex protein that has various effects in the brain. Selank is quite noticeable and very nootropic. In addition to positive effects on brain functioning, it is very good against anxiety, both social anxiety and otherwise. It makes me feel motivation and mental stimulation kind of like an Adderall would, but not so strongly and without any physical effects really, and without a reinforcing nature or euphoria. it's more like an increased tendency towards well-being in your baseline state. Semax is another related compound that is stronger on the nootropic side but less good for anxiety.
I think people can tend to go overboard with their stacks. I used to have a stack of like 15 things, stacking a bunch of different nootropics. I think we should be careful, a lot of these things that come out have barely any or no history of human use, and we shouldn't assume they're all safe. These days I am not always taking a nootropic, as I find that after a good month or so of daily use I tend to need a reset for a while. And I don't know if it's ever good to introduce substances that alter he ways our brain function on a daily long-term basis without breaks for it to operate unaltered. An exception is supplements just providing additional building blocks for body to use to create more natural resources (like choline suppliers and amino acids). I think these can be taken daily long-germ to good effect, and safely. What I take these days, when I'm on a nootropic cycle, is a nootropic (piracetam or noopept generally), with 100-150mg of caffeine in the morning, plus some L-theanine with that and if I ever feel anxious or tense. I take the mushroom powder blend, a greens blend, and a tablespoon of apple cider vinegar in water. I take 5-HTP if I have taken a serotonin releaser recently. I take a choline provider usually when I'm on a nootropic. Recently I have been taking an ashwaghanda extract, to try it out. At night I take L-theanine (I tend to have trouble sleeping as I get older). If needed, I also take oleamide (a great and seemingly harmless relaxation/anxiety/sleep aid), and sometimes L-tryptophan and/or melatonin. That's about it.
There are a number of beneficial herbs, my friend swears by ashwaghanda, I haven't really gotten anything too noticeable from it but it is an adaptogen, which basically helps the body/mind to handle stress smoothly. Rhodiola is one, too, and I do find it pretty effective, also as a mood lifter. There are lots of herbs with effects. They tend to be subtle on the level of nootropics, as in, placebo can be as powerful (placebo is not to be underestimated, after all, placebo pills help depression a significant percentage of the time). However some are very noticeable. For example, valerian makes me drowsy and is a muscle relaxer. I will get tired and relaxed when I take it. There is way too much to herbs than I can or want to communicate in this post but do some research, I'd be happy to give my thoughts on specific ones.
God that took forever to write. 8(
Phenylpiracetam for me, thank you. Expression of D2 for 29% and D3 for 62% in substantia nigra and the striatum, good enough for me.
I have gone through a small tub of phenylpiracetam. It's definitely a mild stimulant. I didn't find it reinforcing or recreational though, it was pretty good for motivation, but probably less nootropic than regular piracetam. More of a stim, but not a stim to do for fun. I never bothered to get more though I might sometime.