I drink a liter of the bitter stuff daily. High quality tea tends to have a near 1:1 ratio caffeine:theanine. Not personally a fan of coffee, which has no theanine or polyphenols (though it has alkaloids/flavonoids/halthful components, I still believe tea superior)
See my profile btw for different sources of sublime Japanese cultivars (Senchas)
I actually strongly prefer coffee over tea, as teas that taste good usually cost more than I can spend, and if they're bad - they taste like water or just bad. That's my experience anyway. Sometimes I do get teas that I like, and I'm willing to gulp down a cup of water-tasting tea if necessary for theamine or other useful elements.
I took a look at your profile - there's a lot of useful stuff there, some of which I have added to my list of "potentially interesting" things. Like Ginkgo and Bacopa. Note that I'm from Europe though, so they may not ship here (I haven't checked yet).
In short, I'm looking as strong (and safe) a supplement for my brain as possible, while keeping the cost very low (I'm rather poor). By low I mean up to about 40eu/year (~3.3eu/month). Coffee doesn't count because I drink it anyway. With cream. Same goes for cocoa - I drink it anyway. So we have a budget of ~40eu/year for whatever else, like theanine and tea for example. Maybe I should create a new thread for that, but I'm still reading on other stuff that may be viable...
Mainly I'm looking to improve my 1) short-term memory, 2) ability to concentrate and hold attention better, 3) energy (while sleeping less especially), 4) perhaps a bit of a mood improvement (been dealing with a lot of stuff lately), 5) improved reasoning, 5) creativity, 6) long-term memory. I know it's a lot, so I numbered them as to how important each is to me right now. I rated them by how much I feel my ability to do these things is diminished compared to how I was a couple or a few years ago (I'm in my 20s). Except for energy, I actually have more energy now, but I want to feel even more energetic, or more clear-headed. Also, more sleep doesn't help, I feel the same or worse if I sleep more, so that's out of the equation.
I think I may have expanded too much. But we'll see what happens with this thread, if it goes nowhere (as it probably should), I'll create a new thread when I will have read enough info on various stuff, I've a few hundred pages more to read, and I'm lacking concentration.
P.S. I can only post 5 posts a day, so I've tried putting as much info as I can.