I have the Garmin 4210 and 18 HD radar. I can pick up lobster pots on Chesapeake Bay with that - Hard to see how it could be improved on in terms of clarity. And yes, it is plug and play. The hardest part with any radar/plotter is going to be the wire runs. But here is what you should really do (It is what I did)
Go to a boat show or large retailer like West Marine and play with all the models you see. Get a feel for how their menus work, how the charts look, etc. That will help you a lot in making a decision.
As an aside, when cruising in the Carib we didnt see very many boats with Lowrance. Lots of Furuno and Raymarine, and a few Garmins but Lowrance not so much