If you have friends at UPS, have them give you a schedule and look at the type of flying they can hold. Compare to what you can hold at Delta. You were hired at at the beginning of the wave at Delta, but who knows what will happen at UPS. I seriously doubt you would see the kinda of deal at UPS Delta offered when COVID started. UPS has and will furlough. Atlanta has a lot of flights and you could drive. Unless you absolutely hate the commute and the passenger side, I'd stay at Delta.