They are two different ball games. Rad-onc is the management of cancer. Rads is the gamut of diagnostic imaging and some procedures.
As for lifestyle, I think rad-onc has rads beat, hands down. Rad-onc is more competitive by virtue of the limited number of spots. As far as compensation, I thinK Rad-onc is comparable or sometimes better than rads depending on geographic location.
As far as getting jobs, I think rad-oncs are limited to larger population areas, which isn't necessarily a bad thing.
The choice depends on what you want to do. I absolutely love rads, but thats just me. I have a friend in rad-onc residency now that absolutely loves what he's doing.
physician salaries survey on the web shows that IR and possibly regular rads is ahead of rad onc median income. I don't know the site off hand but if you google physician salaries you can find it.