These sit in different price classes - KEF LSX II costs roughly 2.6x what KEF EGG 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 |
|---|
| Bass | A | KEF LSX II digs deeper - 54Hz against 90Hz. |
| Built-in power | A | KEF LSX II has the bigger amplifier (200W vs 50W RMS). |
| Connections | A | KEF LSX II adds Wi-Fi, streaming and HDMI. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Cabinet | depends | Ported vs Sealed. Sealed is tighter and happier near a wall; ported digs lower but wants space behind it. |
| Expandability | depends | KEF LSX II: a sub output; KEF EGG: a sub output. |
| Price | B | KEF EGG is cheaper - $499 against $1,299, about 62% less; arguably a different class. |
A KEF LSX II B KEF EGG
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: KEF LSX II measures better, KEF EGG costs about about 2.6x the price% 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. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 90Hz anyway, which makes the cheaper KEF EGG much easier to justify. Think about the whole system, not just the speakers: the roughly $800 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.