Thinking about it, Voyager had a lot of bad/dull characters - Janeway being the elephant in the room. As much as I wanted to like her, Mulgrew was consistently annoying and unconvincing in the role. Harry, Tom, Chakotay, Neelix, Kes... That's some list of nothings. Belanna and Tuvok were good enough, but not stellar. The Doctor was fantastic. Seven was good, but the cynical deployment of her to save a dying series left a bad taste.
TNG was quite bad for it too. Wesley, Data, Troi, Geordie, Beverley. All not great.
TOS was clearly great in this regard.
DS9, amazingly, was all good characters, with the slight exception of Bashir.
Enterprise has T'Pol (more cynical Seven casting), Malcolm, Travis and Phlox on the naughty step, afaic. I liked Archer, Trip and Hoshi.
This is clearly a habit for Trek shows to create a big central character and pal and pad out the rest.
Discovery and Picard have kind of done the opposite. There are lots of really good characters/casting. Burnham, Stamets, Hugh, Tilly, Lorca, Pike, Georgiou - and Dahj, Rios, Agnes, Raffi. But the stories aren't there.
This hadn't occurred to me until now. Could be bollocks. Just flying a kite.