A generation apart: Kanto YU6 is the newer design, against a 2011 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass | evenly matched | Much the same reach (50Hz vs 50Hz). |
| Built-in power | A | Kanto YU6 has the bigger amplifier (100W vs 50W RMS). |
| Connections | A | Kanto YU6 adds Bluetooth, phono and digital inputs. |
| Size | depends | Kanto YU6 is easier to place; Audioengine A5+ is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | Kanto YU6: a sub output; Audioengine A5+: a sub output. |
| Price | B | Audioengine A5+ is cheaper - $399 against $540, about 26% less. |
A Kanto YU6 B Audioengine A5+
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?
The usual trade-off: Kanto YU6 measures better, Audioengine A5+ costs about about 35% more% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. Think about the whole system, not just the speakers: the roughly $141 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.