I have used both Garmin and own 2 Lowrance Units. HDS 12 and 9 Gen 3 units. I was impressed with the Garmin side scan on their big unit but the lesser units were less than desirable in my opinion. Mapping is a must as far as marking wood,rock, ect. and placing wpts on them and being able to return and fish them again without searching. I know nothing about birds but have heard good things. It's like opening a can of worms when asking which unit everyone suggests. Do your home work and study YouTube videos as much as you can. Good Luck and Tight Lines......Ranger