Part of the fun in travelling in Japan is buying the Japanese sweets and snacks. And based on my experiences this time in Japan, I realised that:
1. If getting snacks from souvenir shops, better to get the ones that are also sold in other countries or on online platforms.
Examples: Hiyoko, Tsukigesho, Shiroi Koibito, Tokyo Banana
2. If getting snacks that are unheard of outside of Japan, better to get from specialty stores or counters. And get more of them.
There is a good reason why certain brands have specialty stores or counters. High chance is that their products are delicious enough for the possibility of generating enough sales to justify a specialty store or counter.
3. Specialty vending Machine Snacks may be better than expected
In fact, the best yatsuhashi I have tasted thus far is from a vending machine. Of course, this brand, おたべ otabe, is also available in box form in souvenir stores. But I chose to buy another brand for the sake of trying something new. Well, the good part about this decision is that I realise that otabe is actually better and will be my choice of yatsuhashi the next time I go to Japan.
My guess for its availability in specialty vending machine is due to its popularity (most probably due to its good taste) to justify setting up a machine just to sell this brand of snack.
4. If getting something from souvenir stores, steamed cakes and cookies are safer choices. But they may be just quite nice only, not mind-blowingly good.
5. Mochi and yatsuhashi are risky choices. Buy with a sense of adventure, or buy the ones confirmed to be good.