Download both and give em a try, I believe beertoolspro also has a trial download now too.
"I prefer the latter - it is awesome... they just released an update, and now you can easily adjust your water profile as part of your recipe / schedule. You can do the same with promash, however it's not as tactile as the beertools.
You can adjust /customise absolutely every facet of every input in beertools - be it hops, malt, HLT, MLT, kettle - you name it - it's a right click away."
You can do the same in beersmith too.
Beersmith user here.
Promash hasn't been updated in years I believe which kinda put me off. The Beersmith guy always checks the forum if you need help, I can imagine BTP would be the same.