I flew my first "contract pilot gig" back in 1999 for Parc Aviation. I personally watched my reps at Parc battle for the pilots with the airline on many, many occasions. They are very succinct and intelligent about their approach to dealing with contract issues. Of course, a lot of that was due to the rep who took care of my issues but he did tell me he got his direction from the CEO, who was adamant that they uphold the contract.
I fly for a US Major... so I can be pretty jaded and "hard to please" in the context of airline pilots (further you move up in your career, the less bs you're willing to put up with). I have flown 5 contracts since those days in 1999 and I can assure you that Parc is still the best company to work with/ for. Sure they're not perfect (who is?) but they balance the client relationship for both the pilot and airline quite well. Any agency is in a tough position these days. They have to cater to a very fickle group (pilots) all while competing aggressively for a limited amount of work out there of late. That Parc has weathered the downturn as well as they have I think speaks volumes about their business model.
I'm not working for Parc at the moment, but for me, I would always chose them over any other contract agency.