I do not care much, how they wrote above, functionality is one of the most important, even the design count a bit, as I have to look at that for long hours, that's why I do not really like most of the poker room designs nowadays, most of them are going to the 'funny' free slot mobile games direction. What is annoying to watch all the time.
So the best platform for me is the WPN/ACR from this point of view, too. Betonline/SB is enough good, too. Both could have a bit more improvement, mostly not about the design, but table settings, especially the small window's settings, set ups, personalizing, however it is still okay for me how it is nowadays.