What I don't get however is how people who believe he is self aware, can be so sure. What is your defining criteria for sentience (bearing in mind that whatever your criteria for sentience is, it can be very convincingly mimicked/reproduced by the EMH)
I also think it's a clever program, but I'm leaning towards the EMH as sentient. What's defining for me which could value the argument is The Doctor being self-aware, not just knowing what pain is but feeling what pain is. Feeling what love is, feeling what hate is. Frustration, and sorrow; elements a complex, sophisticated programming like the human brain could achieve.
When the computer or hologram, created to assist and do what humans are told what to do, stands his or her ground and says, "No, I'm not doing that." And states a reason or just being bull headed, it could no longer be considered just a complex program but an individual.
The Doctor has gone beyond his original program to progress as a person. He chose to risk his existence to travel 55,000 light years to save his creator's life; who never could had imagined it would or could reach such a level of compassion. To the Doctor, Zimmerman is his father and would do anything possible to save him. This to me is sentience.
As I've said before, I'm leaning towards the Doctor being sentient.