Having seen both, I'd go with the cheapest/easiest.
I'm a much bigger fan of Swans than I am of Robyn Hitchcock, but in my lifetime, Swans have been a fairly easy act to catch. I'll be seeing them next month, and I've already seen them a few times. They're one lf the best live bands ever, and I have never regretted a moment I've experienced in the sonic vacuum that is their live show.
Robyn I've only chanced to see once. The stars just haven't aligned for Mr. Hitchcock and me.
So I guess it depends on whether or not you've seen each act before, and how many times. But for me personally, I'd go with whatever was easiest.
Hope that helped, though I'm rather certain it did not.
