I have sidescan on my Humminbird that looks 45 degrees to each side, and I find that a lot more useful for trolling - you can move towards the contour that the fish are holding at and follow the school much easier. This is awesome for schooling fish like sockeye, and is really awesome springer fishing in shallow water where your downward looking sonar rarely sees a fish - I can see them as far away from the boat as the water is deep and make a move on them. I've used forward looking sonar also but by far prefer the sidescan.