I use a $2 PD trigger module on basically everything.
The only time I use 2.1mm is when I'm going to daisy chain or do something besides point to point, when I'm doing solar, or when I'm using the connector for something other than power(A voltage divider can protect your input from accidental power connection, so it's one of my favorite simple connectors).
I think they're pretty much all unbranded and look similar, but now there are some with through hole outputs instead of pads to solder wire. If I didn't already have a stash I would probably get those and some right angle male headers.
Just watch out, 12v isn't a thing anymore in the new specs and might not work, best to build around 5v, 9v, 15v, or 20v.
Although usually if I just need 5v, I'm building around a D1 Mini ESP32 module that already has 5v built in.
I saw one in a YouTube build video that allows you to select output voltage / what it will negotiate using a pushbutton, the selection is indicated by the color of an LED (and hopefully persisted when powered down).
Edit: the one chx linked to above is precisely of this kind
I use it when it's 12V, it's probably most popular barrel plug voltage and also used in a lot of audio devices (aside from guitar pedals which have 9V with reversed voltage... fuck that)
-9v is semi-tolerable for legacy reasons, what's really bad is center-positive 5v on what looks like a 1.3mm or so plug, as found in a cheap wireless DMX system. Still beats wired DMX though.
The only time I use 2.1mm is when I'm going to daisy chain or do something besides point to point, when I'm doing solar, or when I'm using the connector for something other than power(A voltage divider can protect your input from accidental power connection, so it's one of my favorite simple connectors).