RealFlex is by far one of the best. RealFlex is TRUE real time and doesn't give you the "Blue Screen" of death that you can get from certain other systems. It's easier to set-up too.
I was interested to read your list, but was surprised to find that RealFlex did not get a mention. Due to the aftermath of 9-11 this solution is quite relevant, due to its QNX operating system. I've found it very stable and hackers will find it difficult to make any impression.
I wonder where a list of top ten scada/hmi companies came from that managed to avoid ubiquitous products like Fix and Wonderware. I am not even real sure these are all comparable products.
There used to be a big gap between HMI, SCADA, and DCS. That gap has all but gone away.
And how do you put Experion in the list without having DeltaV there?