I got the 45 years sampler pack and I enjoyed most of flavours there. Specifically related to teas I really enjoyed the Sublime Matcha, the Power of Green Tea (which I believe someone already recommended this above) and the Uji Houjicha (but didn't like the regular Houjicha which I bought separately).

Outside of that it depends on your tastes really. There are just so many options that is hard to say.