Where do you live?
FedEx total compensation is slightly higher (A plan, 8% B plan, cheaper health insurance for better coverage, higher vacation pay, higher training pay)
Reserve sucks worse at FedEx (1 1/2 hour call out in Memphis)
As Seniority improves-can build miles to use for 1sh vacay every 12-18 months
Seldom deal with the TSA mafia or the Airport Gate lice

Delta-still lots of movement-Bonus makes the pay comparable.
Non-rev very possible, just takes some work
Better reserve system
More places to be Junior or Senior at
Economy's great, so unlikely to furlough--but bonus bucks could easily disappear and the last great economic adventure took guys out w/3-4 yrs of Seniority---don't think it's likely, but possible

Still I'd say flip a coin-Heads for FedEx and Tails for Delta. Catch it in the air and try and figure out which one you were hoping it came up as.