I think it makes sense that you're having doubts about him. To me, it sounds like he is meeting some sort of social need through you. That he's making disclosures because they make him feel good without regard to you. I don't think that's very healthy.

It makes me uneasy that he has told you things that, allegedly, no one or very few people know. The insinuation is that there's a secret that you aren't to tell others that's just between you. And that he has told you that you're his favorite, etc. I don't think a therapist acknowledging a preference like that is in the client's best interests.

Commenting on your weight and acne seems manipulative and passive aggressive to me. I can't think of any context where those observations would be helpful to you. Who does he think he is that he thinks it's appropriate to comment on your appearance? That seems like a huge presumption to me, one that is more likely to be harmful than helpful.

Do you think he has helped you make progress on your goals in the six years you've been seeing him?

ETA - FWIW, I don't know if I'd talk with him about his behavior. I think all too often, clients do this and get manipulated into ignoring their own concerns. I'd keep my own counsel and decide what to do without his input.