A generation apart: Kanto REN is the newer design, against a 2019 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 | B | Kanto TUK has the bigger amplifier (130W vs 100W RMS). |
| Connections | depends | Kanto REN adds HDMI; Kanto TUK adds phono. |
| Size | depends | Kanto REN is easier to place; Kanto TUK is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | Kanto REN: a sub output; Kanto TUK: a sub output. |
| Price | A | Kanto REN is cheaper - $599 against $900, about 33% less. |
A Kanto REN B Kanto TUK
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 TUK is ahead, but only on 1 of the measured areas, and it costs about 50% more. That is a lot of money for a narrow margin on paper - Kanto REN looks like the sensible buy unless something else about the Kanto TUK appeals to you. In a large or open-plan room, Kanto TUK has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Kanto REN is the easier speaker to get right. Think about the whole system, not just the speakers: the roughly $301 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.