David's perfect teaspoon...

I just found this hopefully it will help end the debate
http://blog.davidstea.com/en/how-much-tea-should-i-use-per-cup/

Sounds like its the same as the Teavana teaspoon which is also equivalent to 1.5 bakers teaspoons. I prefer my bamboo Japanese teaspoon to the Teavana one. It’s flatter making it easier to measure out large whole leaf teas. IMO, the Teavana and David’s rounded teaspoons are more appropriate for smaller tea leaves like black tea or rolled teas.