I have a Garmin 76CS colour screen.
Been great. It's all you need in terms of information, and for the aviation specific database, you can go to the 96CS or the new equivilent.
The Garmin is bullet proof in hot or cold, and I have mine direct wired. The voltage regulator in the cig adapter portion isn't needed, you can snip it off, and wire a 24V cannon plug into it. Works just fine.
Whatever you choose, make sure you can use the buttons with gloves on.... seeing as you'll be up in winter very soon....!
Ciao
RH