Re: PTR-91
What, specifically, do you want to be able to do with the rifle (either the DSA or the PTR-91)? Ranges you plan to shoot? What you plan to do with the rifle (paper punching, steel, hunting...type of game, etc.)? What are your accuracy requirements? Do you plan on running a suppressor? Etc.?
Also, which specific models of the PTR and DSA rifles are you considering? Both companies make a fair number of variations on their basic rifles.
Without knowing more details, I will tell you that both the PTR-91 rifles and any of the DSA rifles are reliable, and depending on the model, are all battle rifle accurate (some models are much better in terms of accuracy).