Strange thing happened: I was flying my kite for kite aerial photography and a chinese ((or taiwanese) or japanese) tourist noted my blackened teeth an told that green tea does not color. And it worked ok. Even the cheapest Lidl tea works ok. I bit of acquired taste, but you will learn to love it.
The difference is huge if you have a high quality green tea. Also make sure to use the right temperature to infuse. I would never go higher than 80°C and for some teas I only us 70°C. This is the most important thing a lot of people do wrong. Hotter water destroys the flavor and makes the tea bitter. Also very short steeping times from 1m to 1,5m are the norm.
Another thing noteworthy is that you can actually use a portion of green tea for 2-3 times depending on the quality (on the same day).
Basically every green tea product on amazon, even those in the price range of $50 for a standard quantity, has loads of reviews talking both about how excellent it is and how terrible it is, each bringing detailed points in their favor.
I figure it's mostly due to review warfare between products, but in any case the situation is quite dismal—I investigated something like 30 products and couldn't find a single one that looked like a safe purchase, even with a very flexible budget.
Not sure where else to look since the same problem exists on a larger scale with the rest of the internet since everyone's trying to push their brand or trash someone else's.
Aside from the online merchants you can find small tea shops in all cities usually.
And aside from the quality the taste preferences vary a lot obviously. Most tea shops offer some set/package with a lot of different teas in small quantities for testing.
I think black (red) tea is very much worth it. I just couldn't do without at least a single cup a day. I do brush my teeth afterwards though.
The claim is that the acidity of the tea will soften your teeth and lead to damage from the brushing.
I have tasted genuine Silver Needles but was not impressed.