Vivagreen, as Tudpock says, prognosis is great either way.
If you choose surgery, make sure the surgeon has good experience. ie. You're not the 2nd one he's done
If you choose radiation, make sure who's doing it is very experienced as well as experience can equally affect side-effects here as well.
Specifically re surgery: ask what is the risk of ED/incontinence. Some surgeons may discover during surgery cancer is more widespread and will be aggressive to remove all cancer. This will often determine incontinence/ED. Ask yourself if you're willing to accept this risk.
Re: Radiation ask specifically the areas they will radiate and possible side effects. ie will bladder/rectum areas be affected. Like the surgeon, make sure he/she is experienced.
Best wishes.