I have worked all 3. I was at a 121 regional. Went 135 and during my furlough I picked up a 91 gig flying a Challenger 300. My 135 company just recalled me and I’m going back and trying very hard to get back to 121. Not all 91 jobs are created equal. Mine was was pretty brutal. No set schedule. Pretty much 24/7/365. I want the set schedule and benefits of 122. Really hoping I get the call from Spirit soon.