Different kinds of product: one is active with its amplifier built in, the other passive and needs one. Judge them on how you want to own the system, not just the specs.
| Area | Better | Why |
|---|
| Bass | B | Polk ES15 digs deeper - 44Hz against 55Hz. |
| What you buy | depends | Klipsch R50 PM is a complete system - just add a source. Polk ES15 also needs an amplifier: more money and another box, but you choose it. |
| Connections | depends | With Polk ES15 that all comes from the amplifier you pair it with. |
| Upgrade path | depends | Polk ES15 can be re-amped later and outlive several amplifiers; Klipsch R50 PM ages as one unit. |
| Size | depends | Polk ES15 is easier to place; Klipsch R50 PM is bigger, which usually goes with fuller bass. Your room decides. |
| Price | B | Polk ES15 is cheaper - $299 against $450, about 34% less. Speakers only - an amplifier narrows that gap. |
A Klipsch R50 PM B Polk ES15
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?
Klipsch R50 PM suits you if you want one box, ready to play, with nothing else to buy. Polk ES15 suits you if you already have an amplifier, want to choose the electronics, or expect to upgrade in stages. Neither is the better speaker in the abstract. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 55Hz anyway, so judge these on the other rows instead. Think about the whole system, not just the speakers: the roughly $151 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.