Until very recently I actually worked for a tea company that got me hooked on sencha. I also became familiar with above mentioned teas: genmaicha, matcha, hojicha, kukicha, bancha, ichiban sencha, gyokuro (a finer type of sencha with more delicate leaves).
I,too, have to suggest that you first acquire the taste for these delicious green teas, and let the health benefits be the outcome, not the motive, for this enjoyment.
Although I do not know the statistics or whatnot, green tea is praised for antioxidants, chlorophil, etc that help prevent cancer. And yes, many of the health-benefits are extracted during the decaffeinating process. I have also found the general experience of sencha to be completely lost in decaf, for whatever reason. While an excellent tea for all hours of the day, no, green tea is not a coffee-esque waker-upper.
Tea + health is a huge bang right now. Google it. It's everywhere.
Enjoy!