I'm a pretty anal person, but not well versed in water chemistry, so I started with EZ water. My predicted pH never was correct, and sometimes not even close. So I went with Braukaisers, as it had an easier learning curve than Bru'nwater.
The Beersmith part has been useless for me.
Eventually, I figured out bru'nwater, and really loved it but I wanted to see which was closer, for a long time (several months) I used all three. Braukaiser and brun'water were almost always near each other, and EZ water was way off and brunwater usually nailed my mash pH.
I liked EZ water because it was, well, easy. But it was as much as .5 off on the actual pH, usually less, but still way off- so that made it unusable for me.
I now only switch between brewer's friend and brunwater, but I like brunwater better. I'm trying brewer's friend more and more though, as I want an "all in one" brewing application. Right now, I formulate recipes on Beersmith, and then use Bru'n water for the water additions, and then check it all on Brewer's Friend (because I like storing recipes online). Way overkill, I know, and probably more information that you asked for! But I wanted to share that I've used a LOT of those spreadsheets, and checked the predictions with actual pH measurements and actual beer flavor (been doing this a couple of years now, so have many finished batches to taste) and still give the nod to bru'nwater.