DS9 was much better when I rewatched it a couple of years ago. I had always liked Voyager, but I was dumb and young. Upon watching it in full last year, I still liked it. But only because it was still a dumb sort of fun.
ST:V really needed to stick to it's concept and stop pretending they were simply exploring most of the time. There are great episodes around though, and if you can be patient, they are worth the wait.
ST:V is still leaps and bounds classier than STD though. I was really hoping it was cancelled after season 3, but it still looks like a 4 is on it's way.
It's gross, but I have never seen all of the ToS episodes. I am slowly going through them with my son, so it is taking a while, but we just finished Season 2.