Either clogs or sneakers, depending on how much airport walking I expect (if I have layovers, etc.).

I swell during flight and for a good couple days afterward such that I find if I remove my slip-on loafer-type shoes early in the flight, they are VERY hard to borderline impossible to get them back on later. I need something that either has no back on them so they fit no matter what or where I can loosen the laces a lot.