Having listened to Sonos, BandW and Bose stuff, I'd put Sonos in third place, sonically, with BandW easily top.
A BandW A5 is £400 though..... Although you can get them for £300.
Peter you're referring to integrated, single speaker comparisons and the OP is referring to conventional speaker/amp combinations...
so the speakers themselves can be hardwired
... In this regard Sonos is quite simply the only multi-room system mentioned so far. The Connect Amp, or Connect plus separate power amp with a decent set of speakers is in a completely different league. Airplay, via Airport Express, using third party amps will work in a similar fashion but lacks several features and it's nothing like as good as Sonos. Just cheaper.
You are right though, BandW Airplay speakers are superior to Sonos integrated speakers such as the Play:5 / Play:3 / Play:1 but should only ever be considered in single room solutions. Multi-room? Sonos every time.