Look, you cant go wrong it depends on too many things, the place, the person, the situation...
My feet are probably, far smoother than they should be for a guy, I was never one to go around bare foot to often.. anywho, when I still had a GF, I was new to the whole tickling fetish, and although I love tickling, making it "official" in the bedroom was a big challenge.
I got the full bondage treatment, ankles locked,wrists above head, toes tied back, gagged and nude. A light tickle was the WORST kind of tickle. (in a good way) after a while it's so irritating, you would do anything to move out of the way, and once she had the perfect stroke, I broke down completely. It's not that i was holding back my laughter, it was too light to laugh straight out, but after a while, you lose your mind, like an itch you can never scratch.
I got ostrich feather-ed. they are hella firm, and the tips are quite the doozy, its like a lighter version of the stiff end, but just as effective in quality doses. She got me by running them up and down the centre of my arches, then moving them left and right across all my toes, it was murder by the end, even when the feather was off my feet, I was going crazy wanting them to be scratched to take the sensations away.
If you've never had it done, go out and get it done, I guarentee, at worst, you will have a few laughs, but find the right person and be in the right state of mind, you can get the tickling of a lifetime with feathers...