Depends on if you are more concerned with the "cheapest" software, or the one that produces the best results for you.
Our company has been using PDS for several years and PDMS for the last 3 years. BOTH produce good results. Both have good features and both have their drawbacks. In the end,...if you ask the users who have used both, PDMS comes out on top. Project results and maintenace seem to be better with PDMS. Training is easier with PDMS.
However, BOTH are quite expensive. We use it on major pulp and paper projects around the world. Even with the substantial intitial investments, the results are worth it.
These are just a few observations from our designers.