Up to RPi4 the power efficiency was a lot better, but performance wise you really struggled due to lack of options to connect faster storage. With the RPi5 becoming more power hungry (but also more performant) it is less clear cut, and price wise a refurbished x86 pc isn't really more expensive either.

All in all I would say the benefits of using standard x86 outweigh the slightly higher power use these days. RPis are still good if you need the specific hardware GPIO etc. that is has though. But for self-hosting go for x86 and be mindful of peak loads (these CPUs become much more power hungry on higher clock-speeds, especially turbo-boost).

Efficiency? Worse. Power? Way more.

Big thing is going from usb 3.0 or really weak microsd to sata ssd or especially m.2 nvme.

Pi4 has a72s which are weak, like clock for clock on par with sandylake or even nehalem, and they aren't clocked near as high.

Pi5 is closer to broadwell, maybe Sky-lake, which is starting to hit tolerable performance.