Siblings in Edifier's MR series, so they share a family sound. It comes down to size, output and price.
| Area | Better | Why |
|---|
| Bass | evenly matched | Much the same reach (50Hz vs 52Hz). |
| Built-in power | A | Edifier MR4.5 has the bigger amplifier (80W vs 36W RMS). |
| Connections | evenly matched | The same set of inputs and streaming options. |
| Size | depends | Edifier MR3 is easier to place; Edifier MR4.5 is bigger, which usually goes with fuller bass. Your room decides. |
| Price | B | Edifier MR3 is cheaper - $150 against $250, about 40% less; arguably a different class. |
A Edifier MR4.5 B Edifier MR3
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?
Edifier MR4.5 is ahead, but only on 1 of the measured areas, and it costs about 67% more. That is a lot of money for a narrow margin on paper - Edifier MR3 looks like the sensible buy unless something else about the Edifier MR4.5 appeals to you. In a large or open-plan room, Edifier MR4.5 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Edifier MR3 is the easier speaker to get right. Think about the whole system, not just the speakers: the roughly $100 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.