Mirai O.
A supportive community and teaches coding :)
I was on Scratch for 4 years and I had so many precious memories made there! The vast majority of the community is absolutely lovely and supportive, it's fun for children to code and make friends at the same time ^^ The only negative thing I can think of is that some people (very, very few) report others for fun, when there is no reason to, and I have unluckily experienced this 4 times. It took me at least a few days each time to appeal to MIT as to why I hadn't gone against the guidelines, which, admittedly, was a bit frustrating at times. Although I completely respect that MIT probably can't keep up with all of the different things going on though :)