With third wave specialty roasters, the average consumer can strictly purchase a coffee by tasting notes & roast (filter vs espresso) but with bigger brands, the categorization of the roast provides a reasonable rule of thumb by which coffees can be purchased:
- Light: Fruity, delicate flavors ideal for a pour-over or espresso
- Dark: Strong chocolatey coffee that works well as an espresso or milk based drink
- Medium / Medium dark: Suitable for use in an entry level drip machine
If you wish to order online, check out the STB list of recommended coffees.
The caffeine content does not dramatically vary between roasts so that is not be a deciding criteria - only the flavor profile suited to your preparation method.
Our article on roast types dives deeper into why coffee is roasted and how to recognize it by bean color. Any good roaster, even in a supermarket shelf should mention the roast level. Unless you are buying at a renowned specialty third wave roaster, please DO NOT buy supermarket coffee that does not specify the roast level clearly. Note that the medium roast of a Starbucks is more akin to the dark roast of a 3rd wave roaster.
For non specialty roasters, here is a quick reference table in which you can use the roast level as a filter mechanism to purchase coffee basis your existing devices:
When in doubt, if you prefer milk based drinks, you can err on the darker side, while black coffee drinkers are better off choosing lighter roasts.