The problem for me was partially the characters / development, but partially the cast.
In DS9 difficult to take to characters really grew on me through the strength of the writing and some great performances - i.e. Sisko, Kira and Odo. Even supporting characters like Garak and Rom came into their own.
IMO honestly, I still find characters like Torres and Janeway more believable than the the development they gave Garak or Rom. Outside the context of DS9, they're cliches. A trained assassin from birth suddenly has ethics and morals to help those he grew up hating to help win the war? A idiot that by relation becomes the leader of his entire race? Development or not, that type of stuff is never going to happen outside fiction. While entertaining, the paths their lives took are complete B.S. Torres, Neelix and Janeway are much more realistic because personal and emotional issues usually are a life long battle you learn to deal with on a daily basis and that life continues without some great reward.