Community generalist. The answer is breast and lung.
Breast: well tolerated treatments, simple treatment paradigms, no real need to follow up (most of these patients see medonc every 3-6 months, surgeons once a year, we provide low value in follow ups). They have no side effects for half of treatment, get a bit irritated by the end, you tell them it will all get better, and it does. Sure, you have to deal with the anxiety of a 65 y/o w/ Grade 1 DCIS every once in a while, but overall it's a cush gig.
Lung: well tolerated treatments (really the only acute side effect related to RT that some lung patients get is esophagitis). Easy follow ups. Patients are typically either cured or they do "well enough." Good systemic options for those that recur. Good balance RVU wise for breast, which is lower RVUs.
GU is pretty easy but a bit more annoying. So many treatment options for patients makes for long conversations, especially if you are close to a proton center. Contours are easy but you have more to contour than breast. It does generate more RVUs if that matters. Patients have more side effects that you need to manage, whether they're your fault or not. It's not a hard disease site by any means, there are just things that make it annoying.
H&N sucks. It's time consuming to manage these patients and to do their contours. Patients are extremely high maintenance before, during, and after treatment. Recurrences feel really bad. Some patients just do extremely poorly and you've given them this awful toxicity for them to still recur or even progress through treatment. It's a site that people either love or hate for a reason.
GYN/GI - these sites are ok if you aren't doing T&Os. Somewhere between GU and H&N.
CNS - It's ok, contours aren't bad, GBMs do poorly but you expect them to do poorly. Everyone else mostly does fine.
Sarcoma - also fine