I have been using C-cex from quite a long time and I can say it is trusted. C-cex admin is also very active in this forum and you can get your problems resolved very fast.
Also yobit is good. But I have just started using that, not yet requested a withdrawal, so can't say. But C-cex is good and I am happy with their service.
Yobit is even running a signature campaign from quite some time now, so yeah it should be trusted, at least until now.
How does running a signature campaign make a currency exchange any more or less trustworthy?
That's like saying a restaurant must have good food because they pay people to walk the streets handing out fliers.