I'd get off easy because I'm everything the military doesn't want physically, but if I weren't me it'd depend on the war. I'd serve in World War II or Korea, but not Vietnam or Iraq.
There was no moral difference between Korea and Vietnam (unless you are fixated on the UN authorisation). You got a Communist dictator attacking an authoritarian right wing dictatorship allied with the US, red guerillas in the South with widespread popular support assisting the Northern aggressors and a poor peasant population caught in the middle suffering from combat and US airstrikes.
There are more civilian casualties (bombed damns = mass drowning) and more US atrocities in Korea than in Vietnam, so in that sense it was worse. The main difference is in the media coverage and the attitude on the home front.
It doesnt make sense to OK Korea, but not Nam.