Hello John,
Sorry you find yourself here, but it's a great forum which can give you excellent support.
First thing you should do is to order a copy of the Toolkit - it's packed with leaflets about all the treatment types.
It really helps if you can fill in your profile Bio, so we know what your diagnosis is. This way, we can give you advice tailored to your situation, rather than general handwaving. Click on my avatar to see an example.
You might look at a recent post I did which discussed options, but note it's tailored to that person's situation, which probably isn't the same as yours. The whole thread is interesting, but many parts may not apply to your diagnosis, since it's tailored to the diagnosis of the original poster.
https://community.prostatecanceruk.org/posts/t21432-First-post---time-to-choose#post218948
But whilst doing general handwaving, broadly, the survival outcomes from the two types of treatment are similar. There are some specific situations which can make one better than the other.
However, the side effects of the two are different, particularly if you don't have the option of nerve sparing. This is a matter of considering which side effects are more important for you personally. If you aren't being offered nerve sparing surgery, that might also suggest the cancer is on the rear or lower surface of the prostate possibly with perineural invasion, and that might favour radiotherapy, as surgery might have to be followed by radiotherapy anyway. Radiotherapy alone would also give you a chance of keeping erections in the short term, and perhaps 50% chance in longer term.