best reasonably priced chartplotter gps

[bigeasy1]

I run a Northstar 600 watt Sonar/Gps combo.I really like the unit,especially the Sonar,it performs perfectly,and marks fish,bait and thermoclines easily and will read bottom 500' or more at 30 mph.
The GPS is nice,but I'm not a big fan of C-Map which it has.

My fishing is strictly trolling the great lakes,and I find that Navionics had more features on their charts for that area i fish (Lake Ontario & Erie)
I'm also tired of toggling back and forth on the screen between GPS and Sonar. Splitting the screen makes each window too small.

I've deciced to pick up a separate gps with either Navionics or blue chart software.I was always a fan of GARMIN as they had very user friendly controls and good customer service.I may go with a combo GPS/Sonar unit just in case my sonar on the Northstar craps out.

What do you suggest other than C-Map?? Is the Garmin blue the way to go or is another brand with navionics better?
I can't break the bank on this as I've already got around $1,200 in the nortstar.
I'd kind of like to stay around the 500.00 dollar range without a chip(could add it later)Don't need a lot of bells and whistles,but do want decent charting and simple waypoint marking and go to features.
Any suggestions???