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 | B | Onkyo Creator Series GX-30ARC digs deeper - 55Hz against 60Hz. A subwoofer would even that out. |
| Built-in power | evenly matched | Similar onboard amplification (100W vs 100W RMS). |
| Connections | B | Onkyo Creator Series GX-30ARC adds HDMI and phono. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | depends | Cambridge Audio L R S: a sub output; Onkyo Creator Series GX-30ARC: a sub output. |
| Price | B | Onkyo Creator Series GX-30ARC is cheaper - $349 against $549, about 36% less. |
A Cambridge Audio L R S B Onkyo Creator Series GX-30ARC
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?
Onkyo Creator Series GX-30ARC is the easier recommendation: it leads on most of the measured areas and costs less. Take Cambridge Audio L R S if its size, looks or fit in your room suit you better. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 60Hz anyway, so judge these on the other rows instead. Think about the whole system, not just the speakers: the roughly $200 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.