I think Arsenal has the worst calendar of the 3. Chelsea, at least on paper, have the easiest of the 3, but easiest doesnt mean its easy.
From the current top 10 sides, Chelsea will only travel to Aston Villa and Liverpool. At home we get Arsenal, Everton and Tottenham, which I would expect us to get at least 7 points.
Arsenal will still travel to 4 top ten sides. Chelsea, Pool, Everton and Tottenham. At home they still play both Manchester teams.
City is in the middle IMO in fixtures difficulty. They travel to 4 top ten sides, Liverpool, Arsenal, ManU and Everton. I put them ahead of Arsenal because at home they have a pretty comfortable looking calendar, in which they only host 2 top ten sides, and they are Villa + Southampton.
Of course this is all theoretical, there will be more surprises Im sure, against the bottom 10 sides. I fancy City to drop points at Norwich for exemple. Chelsea will also have some tough games against other sides Im sure, as seen against West Ham.
But from a theoretical point of view, I have no doubt that we have the best calendar whilst Arsenal the worst.