No single best speaker here - they are built to different priorities, and the right one depends on your room, your sources and what you listen to.
| Area | Better | Why |
|---|
| Bass | evenly matched | Much the same reach (60Hz vs 60Hz). |
| Built-in power | evenly matched | Similar onboard amplification (70W vs 60W RMS). |
| Connections | A | Kanto YU4 adds phono and digital inputs. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | depends | Kanto YU4: a sub output; Audioengine HD4: a sub output. |
| Price | evenly matched | Much the same money ($450 vs $449 a pair). |
A Kanto YU4 B Audioengine HD4
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?
Kanto YU4 has the edge on paper, though the margin is not large. The rows marked "depends" may matter more to you than the score does.
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.