I have more than once heard the comment "sencha sucks" on this forum. Japanese greens are often misunderstood and underappreciated, mainly I believe do to unreliable sources of fresh first flush high quality leaf. Plus, it is produced by "steaming" vs. "frying" which creates a whole new taste in green tea completely different from Chinese. It is so rich and fragrant...
I have tried literally for years to find Japanese leaf of consistant quality. I would find one I like and reorder and be terribly disappointed by either stale sencha or sencha that was simply different and inferior from the previous order. But I knew if I kept trying and did not give up, I would find the right vendors for this sensational leaf.
Ok, I have digressed long enough...my favs (I refuse to pick just one fav) are fukumushi cha from Uji, a deep steamed sencha that is very full flavored. I have also been enjoying an everday sencha selection from Kagoshima. I have Gyokuru from Uji about every other day and love it.
Japanese tea in my experience does not get more flavorful with higher grades, but smoother. The more affordable ones can actually be more flavorful and if sourced properly, often more enjoyable. What is important is to be certain you are getting fresh, nitro flushed, ichiban (first flush) Japanese leaf from the most reputable sources. There is some good 2nd flush out there, but I prefer 1st flush.