You need to know what you are wanting to use it for, for starters. Once you know that, then buy one that covers all the issue that YOU think are important. Others can offer ideas all day long. But the final decision is what you want. Most any newer type Fish Finders/Depth Locators/GPS units these days do a pretty good job. As long as you stay with reputable companies, you can't go wrong. If you merely want to see the bottom contour, anything on the market will be good. If you want to see any and all possible fish, then it gets into power and sensitivity capabilities. So either post what you want it for and we can reply further. Or go looking in the sporting good sores and play around with what is on display. They will offer assistance as well. JMHO!