Best Airline Status

Hi! With the year coming to a close, it’s a natural time to do some self reflection (e.g. should I stay in my current job? What should I get with my bonus? Why can’t I get it up?) but perhaps the most important question is that of airline loyalty. I’m based in nyc and travel a fair amount for work and have a decent amount of agency over my work itineraries. I’ve been loyal to United in 2021 but wanted to see if anyone has strong opinions on the best airline status to achieve. I’m mostly interested in which airline has the best benefits that can be used for personal travel (e.g. free upgrades, valuable airline miles for award bookings (looking at you Delta), and upgrade certificates). So, should I stay with United or try out Delta or American? Any input it greatly appreciated and Merry Christmas!