From what I’ve tried I’ve preferred ethyl acetate over Swiss water so far, mainly due to clarify of flavour. I’ve found SW to be more muddy than EA.

Cold turkey and Acetaminophen for two days

My recollection was that my preference changed as the temperature changed, and using Aeropress instead of cupping and having the beans age changed my preference as well. Swiss water was not at the top for cupping but I think ethyl acetate didn’t age as well as the others. Unfortunately I didn’t take notes.

Medical cutting caffein? Decaf still has caffein in it. Much less, but still something like 15mg from a normal 100mg. Just be aware in ase its important.

As to ops question, the quality of the bean matters more than the decaf method IMHO. That said, Swiss Water Process is usually what I end up with, and most of them are ok to good.

Swiss water. I don't do it myself, just buy beans that use it. I feel like it's less bitter than others that I've tried, but IIRC, leaves more caffeine in your cup.

I don't know about methods, as long as it is natural. Beyond that I tend to focus on organic producers.

This one is quite good.

https://www.intuitioncoffee.com/s/order?shipping=true&item=118#H2U5EPBONOJ54O4LHJ722XIT

It's between swiss water and ethyl acetate for me. I think it depends more on other factors like the beans and how they were roasted. There are a lot of roasters in my town, so I tried most of the decafs and have a few I rotate between.

If you enjoy lighter roasts / fruitier flavors I don't think you can beat EA. I've had some really nice EA roasts and drink this regularly in the evening. I think SW isn't as harsh on darker roast notes.

I'm quite partial to supercritical CO2, but I generally like supercritical CO2 for extractions. It's extremely effective, easy to remove, and extremely clean.

Time. I drink the fully caffeinated brew and then wait for my body to decaffeinate.