Taken as a four, there isn't a stronger attack in the premier league than Giroud-Walcott-Sanchez-Ozil. Break to Giroud, feeds Ozil, plays the ball through to Walcott and/or Sanchez. Scary. Hopefully we will see them playing together again soon, after the Bayern Munich preview, at home. Add in Ramsey's runs box-to-box or Cazorla's retention and passing skills and you have a likely three goals per game in the "For" column.
Certainly compares with City's 4+1 (Aguero-Sterling-De Bruyne-Silva + Toure)on the attacking side of things and far outguns it at the other end. Toure's battery is sadly dying.
While Chelsea's 4+1 has been misfiring all season, Man United is miles behind and Liverpool is a work-in-progress.