"peter" writes:

Is a wax ring the best technology to seal between toilet and flange?
Since wax is not elastic, slight movement while attaching (or after
attaching) the toilet back on could cause the seal to become broken.

Any better alternative?

Movement.

I remember clearly the first wax ring I bought.
It was a plumbing supply place in the Bronx over 40 years ago.
Some old guy is standing there with a cigar in his mouth
and he tells me, the secret to a good job is to set the
toilet in plaster.

Being just barely out of high-school, that's exactly what I did.
Put the wax ring in, mixed up a trowel full of plaster and dropped
it on the floor then set the toilet in it and bolted it down.

I never heard that advice again, I don't think I've even seen
it on a.h.r but if you're worried about movement the plaster
is going to be rock hard and along with the bolts, I don't
think there's going to be any wiggling around.