These sit in different price classes - Sonos Five costs roughly 2.2x what Audioengine A5+ Wireless does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.
| Area | Better | Why |
|---|
| Connections | A | Sonos Five adds Wi-Fi and streaming; Audioengine A5+ Wireless adds Bluetooth. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | depends | Sonos Five: a sub output; Audioengine A5+ Wireless: a sub output. |
| Price | B | Audioengine A5+ Wireless is cheaper - $499 against $1,098, about 55% less; arguably a different class. |
A Sonos Five B Audioengine A5+ Wireless
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Sonos Five is ahead, but only on 1 of the measured areas, and it costs about 120% more. That is a lot of money for a narrow margin on paper - Audioengine A5+ Wireless looks like the sensible buy unless something else about the Sonos Five appeals to you. Think about the whole system, not just the speakers: the roughly $599 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.