Blender by a huge mile. Yes, thereβs tons of other software like Linux, of course, but Blender is such a powerful, well managed, economically viable and healthy (community) project that it should be shown as an example of how Open Source should be.
My biggest hurdle with other projects is the fanboys, because many times theyβre quite toxic, insulting everybody who doesnβt adore the project and donβt accept constructive criticism.