B'Elanna was great. Kes was good. Janeway was alright. Seven ruined the show for me.
Seska was a good character but they never really made proper use of her. Samantha Wildman became Crusher from TNG-S1 (of no real point except being a mother of another character). The Borg Queen was overused.
Seven and The Doctor were like Eddie Murphy and Joe Piscopo on Saturday Night Live in the early 80s. I suppose there are folks who think those guys were overused but they were the best talent the show had at the time and the SNL probably wouldn't have survived without them.
Same with Seven and the Doctor. I'm glad the writers and producers turned them loose in seasons 4-7. Others may not agree but I believe it kept Voyager relevant and prevented it from going the way of Enterprise.