I have virtually no experience, but just did a ton of research before ordering my unit.
The Hook2-7 doesn't have any built-in maps. The description doesn't mention any mapping, and there are no variations of the same unit available with different mapping. It will basically track where you went, and allow you to add waypoints, but there will be no reference to land or any navigational markers. It also lacks wifi, which is important to me, so I crossed it off my list.
The Striker Plus 7 (CV is the $399 model, SV is $100 more) doesn't have maps either, and no option to add them. What it does have, however, is Quickdraw Contours. That feature would sway me towards the Striker Plus 7 over the Hook2-7. You can create your own maps with 1-foot contours, and store up to 2 million acres on the device. Check out some Youtube videos. It is really cool. For my use, I wanted mapping options, so the Striker series was out. The closest unit from Garmin with mapping is the Echomap Plus 74 CV or SV, and at $799 or $899, they were more than I wanted to spend.
I ended up going with a Simrad Go7 XSE, made by the same company that owns Lowrance. Built-in Insight mapping w/ the ability to create your own maps, side/down/traditional/chirp sonar, multi-touch touchscreen control (no buttons), wifi/apps. It is totally customizable. It supports Navionics mapping, which has Sonarchart Live, which is, basically the equivalent of... Garmin Quickdraw Contours. It just arrived yesterday, so I haven't installed it yet. It looks really nice, though.