I bought KHS Green a couple of weeks ago, and I cannot stress enough what a relieve it is to have a chainguard. I like the bike, and it works well. KHS has the reputation of making lowkey, reliable bikes. Trek is certainly the more recognized brand name. I like the Belleville a lot, but don't own it. The KHS Green is a very comfortable but slower bike (due to the geometry). I love the coaster brakes, which I find incredible useful when commuting. The brakes are powerful and extremely reliable, which you certainly can't say for rim brakes, which will need adjustment pretty much every other week. It seems for a 5 mile commute the bike would be perfect. (Mine is over 7 miles one way).

But I agree with many others, that recommend to try a lot of different bikes.

I used to be very concerned about winter riding too when I first started this season. And now I found it quite pleasant, you don't sweat but you'll be warm if you get a pair of good gloves, windbreaker and a balaclava.

Best of luck!