I would also recommend JST connectors for most purposes inside an enclosure or on a plain PCB. I found JST-PH connectors to be particularly useful as they are the smallest JST connector which can be crimped by hand even without specialised tools just narrow pliers and a magnifying lamp.

For external connectors go for something where panel-mounted versions are available.

I would recommend:

Barrel jacks for low-current DC power, XT family connectors (like XT60) for high current DC power, also a good idea is to hijack an old USB cable from a mouse for an easy-going 5V power supply from a powerbank or wall charger.

3.5mm audio jacks for low wire count interfaces like UART consoles, 1-wire

RJ-45 or DE-9 (aka DB-9) + cat 5e cable for where you need more wires or a twisted differential pair, think CAN bus, RS-485/MODBUS. These should also work for I2C or SPI although I have not used those in external connector situations.

The above list prioritises connectors which are round (easier to install on a panel or enclosure) and have a large amount of cheap/scrap cables, plugs and receptacles.

For a quick/simple prototype, screwless spring terminals or screw terminal blocks, for something more plug and play but a little more work Dsub-9 (DE-9) - super reliable and super cheap, available as waterproof, pcb or panel mount, solder or crimp, any other option you could want

I would just use terminal blocks - think the kind that have a PCB-side receptacle connector and a removable plug with screw terminals. They have a more secure fit than Dupont headers, no crimping tools required, and they're common/relatively cheap on Digi-Key.

I vote for RJ-45.

0.1" header pins are most common for the hobbyist, and cheap to obtain, but not always the most reliable connection. I like JST-GH for the locking, and small size! You can see some example part numbers used in this connector standard: https://bluerobotics.com/learn/wl-connector-standard/#ethernet-10100

Depending on who will do the plugging/unplugging, the most user friendly way would be USB-C ports and cables.  Even non-technical people know how to use them and won't screw up orientation.

People will propably hate me for that (long distance I2C yadda yadda i know), but i would stay with something like a JST-PH connector and using an adafruit pinout.

I built some sort of vending machine once just daisychaining everything together (plus extra power via XA-connectors). Also these cables are common and realtively cheap and you can combine them with lots of existing sensor modules.

Or just use screw terminals.....