The BEST connectors, period

I think the best connector depends on several factors.

First, how easy is it to crimp or assemble the connector?

Second, how durable is the connector in a high temperature and high vibration situation with possible exposure to moisture, dirt and grease?

Third, how hard is it to find replacement terminals and connector bodies when away from your workshop?

Beyond that, the connector has to have a suitable current and weather resistance rating for the job at hand.

I just bought a crimper and terminals for JST XH. Its commonly used for BMS and battery charger balance lead connections. Not water resistant but common as dirt.

XT60 and XT90 seem to be standards. They are cheap and common and carry a lot of current.

Speakon connectors are good for 4 and 8 terminal connectors at pretty high current.

Weatherpack connectors are commonly used under hood in cars and last a long time in that harsh environment plus you can buy connector kits at almost any decent auto parts store.

I think I have a crimper for AMP Mini-fit jr. Its commonly used for the ATX power connectors on a computer power supply. Very commonly found in electronics, you might have trouble finding terminals.

There are lots more different flavors but that covers most of the stuff big enough to DIY and smaller than what you would use individual wire crimp lugs on.

If you need to work with thermocouples, that gets exotic, then there are electrical feed through connectors, RF, etc.

Most of the time, I think I just look at my existing connectors and try to get from point A to point B without splicing anything. If I'm going from wire to wire, I just look at my list above and choose the most suitable.

I would skip "military grade" mostly for cost but also because if i put a wiring harness where a standard duty connector can't live, i did something wrong.