I am a licensed fishing outfitter in CO. I have Humminbird Xplores and a Garmin Livescope. I'll be adding the Humminbird MegaLive 2 soon and use the livescope for ice fishing. It is really hard to beat the Minn Kota/Humminbird combo in my opinion. The new interface on the Xplores is signifiantly better than what Garmin currently offers as well.
Since your lakes aren't mapped well, whichever unit you end up buying you should immediately get familiar with their charting functions. Humminbird for instance has Auto Chart Live, which builds you your own contour map while your fishing. I fish many lakes that aren't mapped well and its an incredible feature. If you can read maps, your fishing experiences will benefit immediately.
Also, based on what you have currently on the boat, anything you get is going to be a major upgrade. Even going from the Minn Kota powerdrive to a ten year old used terrova will make fishing 10x more fun. The basic features that come with the most basic terrova are incredible - spot lock, follow the contour (of your custom map), spotlock jog, go-to waypoints you dropped on fish from your new graph. Its a blast. If you go with a new qwest motor (came out last year) they are significantly more efficient on battery power and have tons more fun features. Since you're a western fisherman and probably troll a lot, I would look at the Ulterra Qwest too.
The other thing to keep in mind is you're going to want to update/upgrade you battery systems. Lithiums are cheap as AGMs now and they are the only way to go.
Whichever route you go, you need to know that it is really easy to get over stimulated with all the new options and functions. Youtube is your friend. Every company has their own patented technology with copywrites for functions that all basically do the same thing. I saw another poster up above too talk about your budget. You should figure that out before you go shopping. You go to any lake now and you'll see boats with $20,000+ in electronics and trolling motors. It is really easy to get out of hand. Unless you are pro tournament fisherman or you won the lottery, you really don't need 5 fish finders, a 360, active target, and two livescopes/MegaLives
One last add, foward facing sonar is the future of fishing, whether we like it or not. Its incredible even for trolling. If you have down riggers for kokes and lakers, you can set the sonar on your downrigger weights, and watch yourself pull through schools of fish and see how they react. You know immediately if you should change your set up. You also know when you are about to get a bite before it even happens. It is very cool to see and good entertainment for the children. Its amazing for jigging lake trout as well, especially when you are chasing big ones in the spring and fall. Start watching Youtube videos because you should definitely add one to your boat.