Welcome to HW...sorry you have to be here but I think you will find this is a place where you can get tons of information that will help you make an informed decision.
With your stats, it is highly likely that any of the primary treatment modalities will be successful in curing your cancer and that is, of course, your primary concern. Having said that, you might then want to consider the quality of life after treatment as part of your decision making process.
I am personally biased toward radiation and brachytherapy in particular, so you have to take that into account when you get responses from me. Of course it is generally true that those of us who have made decisions for a particular treament are biased in that direction.
You might want to read an active (and somewhat snarky) thread on the first page of this forum called, "Long Term Outcome for Treatment Choices". That references an article that summarizes options and also the commentary from some forum members about that article. On the subject of QOL, I would urge you to Google, "New England Journal of Medicine Quality of Life Study", where you will see a relatively current peer-reviewed study of how patients view their quality of life after treatment.
Re proton therapy, I seriously considered that but was bothered by the fact that most evidence was anectodal rather than contained in long term studies. But, the anecdotal evidence certainly is positive.
Finally, I would suggest reading Dr. Walsh's book, "Guide to Surviving Prostate Cancer", Strum's book and the Blum/Scholz book, "Invasion of the Prostate Snatchers".
Best of luck and please keep us up to date on your progress,