75th RR VS 160th SOAR for a support MOS?

One is an infantry unit, the other is aviation. That's the biggest difference. They have more in common than they have different. If you want to be with the infantry jumping out of planes, fast roping, shooting, and all that, go for the 75th. If you really like helicopters and supporting them, go to the 160th.
Both units produce stellar leaders. Both units are unique in Special Operations because all the members go through the same selection. Everyone in the 160th IS a Nightstalker, not just the pilots. Every person in the 75th IS a Ranger, not just the Infantry. Every Cook, Mechanic, and Supply guy gets out thereon the drop zone to help secure the airfield on an Airfield seizure. Everyone works. That's different than the rest of the Special Operations in the rest of the US Military because everywhere else you are just support. In SF support, you're not a Green Beret. If you go work at Delta or AWG or any other Special Mission Unit there is a separate selection process for the support and the operators. Only in the 160th and the 75th is everyone on the same level.

Both Units are totally Bad Ass. I know guys in both. The SOAR guys are really laid back and the Rangers are not.
No one in a Ranger unit is NOT a Ranger and that is a way of life Young Jedi.

Go Aviation.