In my opinion Garmin and only Garmin. The Zumo would be the "most correct answer". However, I opted for the Nuvi 2595 with Red Pine overlay maps & the Garmin upper midwest fishing guide.
Only slight downside, to using the Red Pine overlay, is that the tracks appear under the snowmobile trails. This appears to happen when enabling 2 maps.
The tracks appear fine on the Red Pine full version, Garmin lake maps, or the built in base map singly. It's just when one tries to layer them. Garmin says they can't help with 3rd party maps, so what ever.
But you weren't asking about maps. Like I said, Garmin has the best. I like the nice large, easy to view and use, screen. I feel the Nuvi 2595 is an extremely good value for the sled, boat, & car. Just be careful when it gets damp outside.