Fedex, if you live in Memphis, is the best job on the planet. Great opportunity, great compensation, your pay per actual hour of flight time is astronomical, great flexibility with line bidding not PBS, and a variety of flying as long as you can handle mostly night flying.
And if you commute FEDEX may be the best place to commute. But commuting long term is a grind. Location can very much determine your best choice.
But if you don’t want to live in Memphis and want to live in ORD, the Northeast, the West Coast, Houston, or Denver, then United just might be a better fit. 2 years approx to get into Denver/ORD/IAH. You will fly more hours yearly, take longer to make Captain or get to a Widebody, deal with way more customers and taxiing in and around terminals, and get to wear that stupid hat in the fall and winter unless it magically disappears like the Captain’s did years ago when he left it on his pension one night. You will fly nights too at UAL on the widebody and the 737.
Full disclosure: Hired both places. Was in Fedex pool over 2 years while at United. No doubt would have gone to Fedex right away. Was my number 1 choice, and would have moved to Memphis. But stayed at UAL and no regrets. Like the mix of flying and living in base and company trajectory is good. But hey I am an airline pilot and so what do I know?