So you want option three, to take advantage of donated labor? Basically, as long as you get free stuff, you don't care.
If you don't want to give someone money for their time and labor, and you don't want ads. Just don't use the thing. You don't have to be a dick about it alongside.
Now if you want to talk about the merits of Free Software, as in freedom, and how sync doesn't adhere to that. That I would be more engaged in. But it's pretty clear that all you want is free stuff made by other people donating their time and effort, with you benefiting.