I seem to play more at Rival Casinos, not so much because of the software, I think all of the major ones are very good.  I think its important information which is why this site breaks down the casinos by platform such as Microgaming Casinos, playtech casinos and so on. 

I think I have always payed attention to it, to make sure its not some bizarre proprietary software and I can know right away which games I like to go to.