Humminbird 598 ci HD SI.......
http://fishfinders.factoryoutletstor...FSRk7AodIEAAYQ
Unless you want to go bigger. Then you move up to the 798 or 998's.
The ability to have GPS and mark places, brushpiles, ledges, humps on the maps (you'll need to spend $$$ on a Navionics map card) is invaluable. Being able to look to both sides and spot structure way off the sides of the boat, awesome.
Seeing all the contours of the lake BEFORE you get to them?? Priceless!