I don't know why so many people think we'd beat Arsenal. Yes, Bradford beat an almost full strength team but don't forget the difference in quality of the pitch. I think both Arsenal and Swansea would comfortably beat us. In answer to the question, I'd prefer Arsenal because they have a better all round team and the atmosphere would be better.
^This^ although I'd substitute "would comfortably beat us" to "should beat us"
We're on a decent run, but it's only 3 games and we're talking about one of the leading English clubs of the last decade (albeit off form) and the surprise form team of the Prem this year. Yes, we beat Newcastle, but they are woefully short of form & confidence so either the Swans or Gooners will be a different proposition altogether.
We have a decent chance, but either Swansea or Arsenal will be strong favourites.
I think the atmosphere will be better for Arsenal, so that's who I'd prefer. Plus I have a Gooner mate who I would very much enjoy seeing for a beer after if we do knock them out!