Coffee.

The reason I answer this is because it is such a spectrum of possible solutions.

Diner coffee. Folger’s. Starbuck’s.

Then there’s whole bean, grinders of various types, machines and preparation methods… and if you go all in you can roast your own beans.

And it’s all about relatively subtle differences in the finished product - to the layman.

I can’t regularly afford the coffee I prefer but can order from Amazon. I stick to the local grocery store espresso beans for the most part.