DM, the point of having a diagnosis but needing to decide on treatment is probably the most stressful stage in the whole process.
The fact that you have two options means that from the published clinical data there is no difference in outcome between the two, usually measured in the rate of relapse (based on PSA). But remember that by definition data on 10-year outcomes is based on treatment over 10 years ago, and the technology has improved since then.
I chose surgery; I was 63 at the time and the usual advice is that surgery is better for younger patients (in PC terms!) and radiotherapy for older. That is because surgery involves some pretty traumatic damage to your body internally, and the younger you are the better you are likely to recover. Everyone is going to have issues for quite a few weeks, if nothing else you will be needing a catheter until the urethra heals. Once the catheter is out you may have incontinence issues (needing pads to absorb leaks) which can recover quickly or slowly or not at all. And everyone has erectile function issues for months and for many this is ongoing. The good thing is that if you have a relapse after surgery radiotherapy is still available as a second hit, that isn't often possible the other way round.
Radiotherapy is usually given in combination with hormone therapy (androgen deprivation therapy) which has its own issues. But radiotherapy alone has less severe effects in the short term than surgery; there will probably be slower and longer term issues with continence and erectile function. The big worry is spillover of radiation triggering cancer developing in nearby tissues (bladder or rectum) but that takes around 20 years so is less of an issue in patients when they reach 70 or so. However the hormone therapy has its own problems, while it contributes to fighting the cancer and is crucial if it has spread beyond the prostate (not your case it seems) it is imperfectly reversible with a risk of long term drop in libido.
Having said all that, the new generation of radiotherapy machines allow better targetting than the ones of 10+ years ago, which means they should achieve the same curative benefit with fewer side effects. And for some patients using hormone therapy is no longer necessary, it would be worth asking what they recommend in your specific case before coming to a decision. Surgery is also likely better now in that the "robotic" methods were relatively new 10 years ago and not universally available and there are now many more machines and surgeons experienced in using them.
Tough decision, there isn't really a "right" answer it just has to feel right for you. Make yourself fully informed before deciding. Good luck.