Really like my Polaris 9550 Sport. It climbs and cleans walls very well. It, like others can not clean above the water line, so I will brush my built in loungers, table and top 2 steps off before I start. I eventually need to clean the scum ring around the top water line occasionally by hand, which is easy for me as I have fiberglass and use a scrub sponge. So while a robot today is 100% effective it saves me hours of pool cleaning a week.
I like mine in that it has 3 large removable/washable filter options. It comes with a general usage one. I own the option sand/fine dirt one, as there was a lot of red clay in pool once it was completed, and this cleaned it well, and I still get grit from peoples feet. It also has an optional leaf filter too.
The thing I like most about a robot - I can go drop it in and run it while doing other stuff, so great if we invite some people over in a couple of hours. Let it run while we set up other stuff.