Power also plays an important role. The more power the better the echo detail. The better the echo detail the better the ability to read and understand exactly whats under you. I did alot of comparison shopping when I upgraded and went with a Bottomline tourney master. Pricy but I can see a pt wilson dart go up and down at 150 ft of water. Even if Im jigging it only 6 or so inches up and down. I can distinguish how dence the balls are and easily read the bottom at cruising speed. And still see all detail. This is very imortant when searching for bait! I also had both transducers and used them both! You can actually use 3 with this unit. Im not saying to go spend the money but I think screen size, readability and power are the main concerns. The down fall to the Bottomlines is the contrast sometimes cant be adjusted to clearly see the screen due to sun rays ect. And Like AK said! "never use auto mode". Turn the gains up pretty high to start. I used to run mine all the way up. Some people turn them down till they cant see anything and never know whats really under them.

Bob D