We know that Yondu didn't deliver Quill to Ego to spare him the fate of Ego's other children. But this creates a problematic dichotomy.
If Yondu knew that the children he delivered were being killed, then the fact that he kept Quill does not redeem him because of the staggering number of deaths he allowed — enough to fill that cavern of skeletons.
But if Yondu did not know that the children he delivered were being killed, how did he learn that right before picking up Quill, coincidentally the only child with the celestial power? And surely, after the hundreds he had delivered whom he never saw again, he would have caught on.