Yep, go with color if u can $$$$ it.
The best one is the one you research and end up with on your boat. I think they are all good.
For your price range.
Look at Eagle Fishelite series
http://www.eaglenav.com/en/Products/Fishfinder-Chartplotters/And the Lowrance LMS series
http://www.lowrance.com/Products/Marine/Full-Size-SonarGPS-Chartplotter-CombosOr the Humminbird 500 series or even the 300's
http://store.humminbird.com/ccombo-ccombo500.html It comes down to, Display Resolution (like 480 x 480) the higher the better, Screen size (for your price about 5" is it).
Then decide internal or external GPS reciever, I like external just so I can share (network) with other units on the boat and to be able to trade up units as time goes by and keep the old GPS reciever.
Also consider internal Lake maps or purchase you own separate (on SD card). I like separate purchased card again so you can trade up (and trade in) and keep current.
As you have more specific questions, ask away.