I'd say taste. When I began seriously my tea adventure, I wanted to try everything, every variety, every variation, which is virtually impossible I guess. But this way, I discovered the very teas I enjoy the most now, mostly dan cong, yancha and sencha. But I couldn't have discovered this without the help of others. Sometime, reading the love that one has for something makes you want to try it ! And I'd say I am grateful to this forum to push me towards Japanese greens (and teaware). But my wallet does not thank you for sure !!
Ippodo's Rimpo gyokuro : 10g/10cl, 50°C/2', 60°C/15", 70°C/30", 80°C/1', 90°C/1'30. Simply wonderful.