As far as actual character development goes, I'd have to say DS9 wins in a landslide. That show did more to flesh out its characters than any other Trek series. However, Voyager does
have an insanely fun cast. There are a few boring characters, like Chakotay and Kes and Kim. Although maybe they were just boring because they were never given much development. In any event, the Doctor easily had enough personality for several
Also, anyone who says Seven doesn't have a personality is clearly not paying attention.
I do wish that Voyager had had more recurring characters. That was one of DS9's greatest strengths. But other than a few bland background characters, like Ayala and Samantha Wildman, there's really just the main cast. The writers had a crew of 140 or so people to work with. They could have done so much more.