In unlikely event of the race being close, Manchin. I'm not a fan of him, but demonizing him by many Democrats is kind of annoying. It's almost always better to have a Blue Dog Democrat than Mr. Generic Republican, especially as dumb as Raese.
Otherwise, I'd vote for Johnson.
Joe Manchin is likely to switch parties in the event Republicans take over the Senate
I'm not so sure about this. West Virginia really do like conservative Democrats. Why would Manchin join pretty pathetic thing statewide WV GOP is?
That isn't to rule out Manchin becoming an independent, though...
Very true, though I firmly believe he will stick with the D's. He has taken a very postpartisan approach to legislating; he seems to direct his criticism at both parties.