Personally I cycle, I also have bad knees and I do think it's easier on them

I'm long legged and can second cycling. It can be hard if your area isn't flat, but it's low impact and can serve as a healthier way to go grab groceries

you need to try different things to find what works for you.

there are tons of different ways to exercise. running is just kind of easiest because it has no equipment, training, etc requirements.

swimming is better than running for sure, but it requires access to a pool/water.