All I can really say is ... here's how my thought process would go :: dons his shoddy imitation Rick Berman cap ::
I'd start by trying to imagine the series trajectory after each one of them was removed? Do I like where I think it's going, does it have no impact at all, or does it hamstring the series? Janeway's really the only one that must stay.
Second, is there a way to determine likely financial impact on the series (ratings)?
I don't think there's any character (again, other than Janeway) that would by itself make that big a ratings difference, but approaching it from another angle, ratings are steadily and slowly dropping, so what are the new trends in shows that are getting the 18-35 demographic excited? How does Voyager, as a TV production - not just Star Trek, compare to what is currently out there? Is there a way that I can turn the series toward any of these trends, and could that be done by sacrificing a character for another?
Third, could writers still tell the same kinds of stories they want to without the character?
Here's where I think Torres, Tuvok, and the Doctor get saved.
Fourth, how do I judge the work of each actor in front of and behind the camera?
Here's where Paris gets saved. By most accounts, the guy seems to have worked his butt off behind the scenes.
Here's also where Chakotay and Kim are in trouble - one is a malcontent, the other is immature and unreliable.
Neelix and Kes are both redundant in that they are both DQ characters that have minor roles on the ship and can be used in a similar way, thematically, by the writers. Each can have a back story filled in for them to interact with any other new aliens-of-the-week that we want to introduce. Between the two, we need to keep one, and Philips is the better actor so that disadvantages Kes.
So, we are down to Chakotay, Kim and Kes. At least Chakotay has the native american backstory to draw from, if we can ever figure out how to use it. Kes has mental abilities we can probably use, but any story that requires something like that, Tuvok can probably take care of.
In order of most likely to least likely to let go, so far I'm thinking
Kim - from a writers' perspective, a very replaceable character and an unreliable actor
Chakotay - under/un-utilized potential with an actor who doesn't want to be here anyway
Kes - under/un-utilized character with no clear direction on how it could be used.
What's the financial impact of letting them go? Here's where contract terms of the individuals come into play.
I don't know how that affects anything since I don't know what their contracts were like, but that may re-order those three somewhat.
Otherwise, there's the answer - Ensign Kim, you're out.