I have a HDS 7 gen 3 and love it. It does side, down and 2d really well, it has clear pictures. I don't have any experience with a newer bird but both Lowrance and bird sell good top of the line sonar. Some people might prefer one brand over the other but the truth is that there are literally thousands of people who love each brand and swear by them.
One thing to consider though, if you plan on networking a trolling motor through your unit then you have to choose what trolling motor you want and then go with the sonar that will work with it or vise-versa. Currently, the only options that will network together are Lowrance/Motorguide and Minn Kota/Hummingbird.