Do you trust these cheap boxes for security and having a flaky bios?
Pre-loved ex corporate mini machines. Dell or HP are my go to but I would aim for an 8th gen Intel CPU as the oldest. Bags of power compared to single board things and usually the idle power isn't a long way off them either.
Sorry for not articulating the topic very well.
I wanted to start a general discussion on the hardware people use for their builds, whatever the purpose they had in mind.
Most Linux sections of forums tend to be about software, so I thought it would be interesting to cover the hardware side of things.

One downside I've noticed to this BeeLink box, the wifi performance is absolutely shocking, and it looks like it's a fairly normal issue.
I didn't test the performance on Windows, but alas until I get the cabling wired up from downstairs, this won't be able to work for my daily driver. I actually ran into a problem trying to download from a repo with curl timeout (Operation too slow) which was interesting.
Fortunately, I still have my trusty mini-itx build, but it's footprint is significantly larger than this. But it has much better wifi.
That's one reason to choose a relativley modern ex-office refurb PC over a 'designer' ultra SFF box - you can upgrade the hardware just like a windows PC if you want to.
It's a bigger box though, so it really depends whatyou want.