I am a 1P on United so I rarely fly anything else and now I know why.
Flying OUT of SLC the lines at ALL TSA checkpoints for Delta were unbeleivable, worst than any I've ever seen in LAS.
And they are even ruder than usual and the same belt buckle that goes through dozens of other airports won't at SLC and I was using the "International" gat because the regular one was into the parking lot...no exaggeration.