IMHO, If the ethical reasons are first for you, points 1. and 2. of my first post, then the choice of Liberapay should prevail.
Similarly, if economic rationality, point 3. and 4. predominates and the euro costs you less.
We can hope that there will be visibility for donations via Liberapay in a future, if my request to promote this system in the same way as others is taken into account.
In other cases, it may make sense to use other means of giving.
Thanks you @apple-muncy for link 😉
It seems to have two problems in my case :
1°) It's looks like impossible to do a single donation [My goal is not to finance the pool 😉]
2°) The "MUST Sign In" boring me for all :-((