I believe Brian sums it perfectly.
We have tried both major clubs but have stuck with the C&MC as we found the other not to our taste. We do however rarely use the club sites and really only keep the membership for the CL's as in our opinion the club site fees are exorbitant and it's a real faf booking them.
We are also members of the MCC which is a pleasant friendly club though limited.
As Brian since the 70's we spend most of our time abroad at the same time period as him, also using ACSI as well as Municipals and Aires. In Europe we have never booked a site in advance, and won't into the future, with never an issue. We have done this every year except during lockdown where we only visited our family, when allowed I might add, staying on their own property. The motorhome really came into its own then allowing us to see each other safely.
Personally, in answer to your question, I would do as we did and join both main clubs and try both out during the membership year and drop the one you dislike from the second year, or both of course! At least then you will be able to make a fair comparison on your own knowledge rather than accepting others opinions.
Bas