None of those alternatives will do any better than the original. In fact' some of them (like the headlight connector) have the exact same terminals as the original Sumitomos. Anything that comes with wires permanently attached requires soldered or crimped connections to the original wires, which means 6 more places for something to go wrong. Terminal blocks are susceptible to the same corrosion as crimped connections plus the possibility of the screws coming loose due to vibration. Ring lugs? Really? And the Anderson Powerpoles, while excellent connectors (larger versions are used on the batteries in electric lift trucks &c), are made for #6 wire.

Any connector you use there has to be rated for at least 100VAC and 10A. The 3 pin version of these would work except that the glands where the wires go into them are designed for round cable, not 3 individual wires so they wouldn't seal.

On the other hand, many of the original connectors are still working exactly as intended 35 years later, some with several hundred thousand miles. The ones that fail are usually the result of not being maintained; All that is needed is for them to be unplugged every few years, any foreign matter (dirt, insect nests &c) removed and maybe given a spray of contact cleaner &/or a water repellent oil if they are used in extreme conditions, although just the action of unplugging & re-plugging should be enough to push the oxide out of the way and make good, fresh contact again for most. If an oil is used the connector should be maintained again every year or 2 because dirt will build up in the oil. I use an oil (RustCheck or similar - must be recommended for use in electrical connectors) in connectors on Eccles for winter use on salted roads but nothing in the ones on Mr.H for summer use.