I'll say para milli or milli. Really, with the possible exception of not liking liner locks, if you can carry the milli every day (no easy task, mind you), no reason not to. Lord knows I would if I could. That thing is ginormous though.
In the more general sense, you'll want G10 scales so it doesn't get slippery. A sandwich construction might make it easier to keep clean and dry.
You'll be wearing gloves, most probably, so I would look for thumb studs or relatively large spyder holes (like the military and paramilitary have).
The AFCK is also a good choice. Though I personally don't find it attractive.
Might also investigate the Manix/Mini manix. Not a big fan of lockbacks myself, but a pretty fantastic knife nonetheless.
I'd look into the Bump and Spec Bump, two recent interests of mine. The Spec Bump particularly might be good for that weather. The assisted opening might be nice, and the 3d G10 scales would be useful.