Best first impression tea... Technically I have two, because there are two specific moments I can think of where I just said, "Wow."
The first time was after my mother gave me my first teapot (a Japanese beehouse pot) and looseleaf teas from Argo Teas. I tried their green chai, and was just blown away. I still drink it today, though I'm not sure if I'll be able to find it to order again.
The second time was after I came back to Korea, and bought my first Korean green. I had been drinking deep steamed Japanese sencha daily, but grabbed a canister at the local mart and tried it out. I had had to translate one of the words in their description, which turned out to be "soft" as in "soft tasting." It was very true. Since then I've been hooked.
Today's tea day has been really interesting. I picked up a small travel set while I was in Daegu and brought it in to work. I decided that I wanted to use up all the rest of my Teavana teas so that I have room for new and better things, so I brought in my canister of their Ayuverdic Chai to keep at my desk. My students (all in elementary school) were so intrigued by the smell and watching me brew that they all begged me for tastes and LOVED it.
It seems I may have inspired future teaheads, even off the low quality stuff.