"Steve" wrote:

More than 90 percent of all sparklers worldwide are tank
fermented, I would guess.

I am obviously not qualified to provide my own opinion, because
I've only just found this out, but which method produces the
better wine?

Well, judgment is pending. Riddlers of course state that the small
vessel intensifies the contact of the lees with the wine and that
this will result in better quality.

Tank fermenter otoh - especially some sitting in German viticulral
schools - insist on the fact that both methods are absolutely
identical, that finally a tank is nothing else than a very, very
large bottle.

There is a kind of "pragmatic" truth: Tank fermented sparklers
with reduced costs supply the lower end of the market, while
bottle fermenters, being able to command higher prices (by law/
tradition/marketing/whatsoever reason), can afford better quality
base wines, longer lee contact etc. resulting in a finer finished
product.

So, unless someone takes the same base wine from champagne that
goes into a regular cuvée and makes a test putting this wine into
a tank for the same rather long time - up to half a decade and
more for the very best -, nobody will know the outcome. Anyhow,
this happens legally to be a strict no-no in Champagne.

As to medium quality base wines (viticultural schools don't
normally have access to the very best) with rather short time on
the lees - less than half a year in any case I've heard of -, the
Germans say there's no discernible difference.

HTH to clarify a little,

M.