You will find almost as many recommendations for knives as the models available. Here are some of my recommendations. The Ontario Rat 7 in D2 steel plain edge (not serrated) is my current kit knife. Not too big, not too small, and the sheath has a pouch for a small survival kit (or fire making kit might be better in your scenario). Other knives I would recommend include the KA-Bar Becker knives, either the 7 or 9 (extra pouch on sheath as well). The Cold Steel Recon Scout, Trailmaster, or SRK also come to mind. I must admit mine are the old Carbon V blades and I cannot speak for the current production models but my Cold Steel Bushman is made of the same SK5 steel as the recon scout and trailmaster and it has taken a beating and is still going strong; also the SRK is made of the same AUS 8A steel that made their original tanto so tough.

Others to consider (I say consider only because I have no personal experience with them) that look promising: ontario Ranger series RD 6, 7 or 9 (available with orange handles and pouch on the sheath); the ontario ranger afghan got a good review in tactical knives as well; Gerber big rock camp knife; and for a good stainless option, the SOG Seal 2000 can be had with a nylon sheath with pouch (if you end up needing a shorter blade there is the seal pup).

As you might be able to tell I prefer a larger blade (I also tend to stick to production blades as custom and semi-custom are a little too pricey for me). In your scenario I would probably consider a shorter blade because it would ride more comfortably on the snowmobile (although that certainly wouldn't prevent me from trying to carry the rat 7). My thought being that with the knife on your person (instead of in your pack) and a fire making kit in the sheath pocket that even if you are separated from everything else you can still make an improvised shelter and a fire. You should consider whether a stainless blade is necessary or not. I wouldn't hesitate to use a carbon blade and bring along a tuff cloth to help protect it from the elements. You may want to be able to handle the knives before you buy. In the end it will be what you are most comfortable with. Nothing wrong with a buck 119 Special you can still buy at Wal-Mart. Standard disclaimer, no affiliations with any companies listed here, no kickbacks, etc. Also you might consider any safety issues on carrying the knife on your person while riding the snowmobile. Would like to know which blade you end up with and how you plan to carry it.