F&F is right. It's a personal preference and experience thing. I've heard a few bad experiences about Lowrance not lasting more than a few years. I think that's user issue and they didn't take care of their graphs. If you take care of them, remove them from boat after use (if kept outside) and keep them clean, they should last many years.
On sale for $1,200 now at Cabelas. You don't need the structure scan module with touch units. All inclusive with Insight mapping. Best bang for the buck at that price range.
http://www.cabelas.com/product/Lowrance174-HDS-7-Gen2-Touch-SonarGPS-Combo/1421711.uts?Ntk=AllProducts&searchPath=%2Fcatalog%2Fsearch.cmd%3FrecordsPerPage%3D18%26No%3D0%26N%3D0%26nl%3Dtrue%26Ntk%3DAllProducts%26Ntt%3Dlowrance%2Bhds%26search%3DSearch&No=0&Ntt=lowrance+hds
If you're targeting walleye and stripers, you need side scan. Helps reduce a lot of wasted time.