I downloaded trial versions of Promash and BeerSmith 2.0. Personally, I found the BeerSmith user interface to be much more intuitive. They're both only $20 to $25 so I didn't spend a lot of time weighing the pros and cons. I just found that with BeerSmith I was able to navigate and modify recipes faster and more easily so that's what I bought. Six months later, no regrets.