There are so many options, at so many different price points.
It is all very confusing, especially with all of the re-branding going on.
Reading all the various pool robot posts on the forum, Dolphin seems to be the top choice. However Dolphin/Maytronics are also branded as "Pentair", "Doheny", etc...
Most people do not find the some of the "extras" such as remote control, bluetooth control, etc...worthwhile. The top loading basket seems very popular.
With all of the various Dolphin options I think that in general you get what you pay for. So, the bigger your pool or the more trees/debris you have, the more likely you are to be happy if you spend more money. Having said that, if you shop around a little, or find the internet version of a particular model (i.e. buying a Doheny Discovery instead of a S200), you may save a few bucks.
I have a 20'x40" vinly pool and I just bought a Dolphin Nautilus Plus. So far, so good. However, I don't get a lot of leaves in the pool. If I did get a lot of leaves, I think the baskets on this model might be too small.