I have not seen any significant or widespread views that even 4gb of ram is detrimental to performance.
I suspect there will be very few people who will have usage where going from 6 to 8 will make a tangible difference.
Instead decide on the internal storage, not the RAM in my opinion.
Personally, when my budget allows I am planning on the 128gb version for that reason, the capacity.
No idea what my usage would actually be, and that is more to future proof my decision as expanding via MicroSD isn't an option.