I would strongly recommend
Sonos. They offer speakers in different sizes and more importantly they play well with Apple and Android products and you can stream directly from a NAS or a desktop computer. I think you can even play internet radio directly from the units themselves. Their Play:1 and Play:5 models are resistant to humid environments which makes them great for the bathroom or if you plan on bringing them outside at night for BBQ's or parties.
They support pretty much all the requisite file formats such as MP3, WMA (excluding DRM protected files), AAC, AAC+, OGG, FLAC, Wave, AIFF, iTunes Plus and Apple Lossless.
They utilise your existing Wi-Fi network, rather than Bluetooth connection to your phone, so wherever you have Wi-Fi coverage in your home (which is probably everywhere), you have music. If Ethernet is your thing, they have built-in Ethernet ports as well.
The sound quality is pretty darn good for the size of the speakers with surprisingly decent low-end frequency response. They are a bit on the pricey side, but out of all the various wireless speakers I've looked at and used, these offer some pretty good bang-for-buck.
The only negatives I've found with the Sonos gear are:
- If using Wi-Fi, Sonos devices support 802.11b/g 2.4GHz networks only. No 5Ghz support.
- The
Play:5 model contains two built-in microphones. If you're security/privacy conscious, this is a bad thing. According to the Sonos website:
"...two built-in microphones to enable future enhancements of Trueplay tuning. (Microphones are currently non-functional. Users will be alerted when microphones are functional and active)". Sonos haven't indicated whether there is going to be the option of disabling the microphones after the future software update enables them. The other models don't contain microphones.