Selfhosted

Lemmy has relatively good search, usually if you remember bits of the title that works?

In any case: Both n100/n150 and raspi are in the <10W range. Obviously raspi is lower, but also A LOT slower and much worse connectivity. As the price is roughly comparable, I'd go for the much more capable N100/N150. Only go the full 'minipc' route if you don't mind the (probably) higher power usage, which can depend highly on model. Older (but cheap on eBay) models can be 25W on idle.

Depending on what you actually need, I'd setup a Sync thing or NextCloud or something and go from there.

I have a FriendlyELEC NanoPi R4S with metal case, running Armbian with a couple of USB SSD drives, for file and website hosting mostly. Just my personal use: no heavy loads. It's air cooled (no fan). It typically reports a temperature of about 35 centigrade. Up into the 40s if I increase the load (development, upgrades, indexing, etc.) I don't know the actual power consumption, but the power adapter is only 15w. My original NanoPi R1 works fine for the same purpose and uses even less power - runs cooler. I got the R4S and an R2S Plus, so as to have spares and development/tinkering systems and to have a 64bit CPU, in case I wanted to run anything that requires it.

It's not upgradeable but it's fairly cheap and has worked well enough that I haven't wanted to upgrade it for years, other than migrating from the R1 to the R4S, as mentioned. If by dev workload you mean running local LLMs or heavily loaded CI build system it probably wouldn't be a good fit, but fine for compiling a package occasionally, local git and npm servers and similar. I don't recall when I got the R1: some time before Covid. The R4S and R2S Plus have been running for about 5 years now.

There are many other SBCs supported by Armbian. You might find something better matched to your requirements.

Compare the processors at Versus.com for a rough overview.

Regarding strictly cpu/power consumption ratio I guess the mac mini is pretty good.

If you want something that fits the SFF cube shape so you can throw it next to a TV or desk for video output, you can probably go for the SYS-A22GA-NBRT.

Easy to upgrade CPU & RAM later down the line if you start doing more stuff with it, plus space for dedicated GPU if you ever want to do heavy media server stuff.

Would avoid pi due to the underperformance for the price. Plus best bang for buck usable storage will always be HDDs. SD cards are nice but you have to disable journaling to keep the writes low as to not wear down usable blocks.