to put it simply, you can't compare cause these are very different products (for features, support, cost).
If you are looking for low cost or free products there are several listed here
each product gives some advantages,
DW SIM (dwsim.inforside.com.br) is open source, has a decent GUI (based on NET) and the VB code is not difficult to edit,
alternatives as COCO (
When comparing accuracy, stability and convergence, thermodynamic libraries are on the same level of best simulators,
however, if you need to solve networks (with many operations, recycles etc.) or require specific operations (such as heat exchangers, multiple controls etc.) products as Aspen (