In my opinion, Chelsea are currently in a much better form than Arsenal, they had a very easy draw for the Champions League that allowed them to gain a bit more confidence and a boost to their spirits and their arguably less deep squad will have had two more days to recover from their international bout than Arsenal. So the Chelsea win is a no-brainer.
Keeping in mind that Chelsea's attack is in great shape while Arsenal are still not toothless, I'm also going with over 2.5 with a two to one Chelsea win being the most likely result in my book.