Your Favourite First Growth

but for subtlety, depth and breadth, charm and down-deep-in-the-soul balance and harmony, for me it's Haut-Brion. More than any of the others H-B when properly aged can drop down into a dark chocolate, tobacco, then a startling deep, dark plum flavor backed up with violets, that none of the other growths muster in quite the same way.

Nice summary.
I think sometimes Ho Byran Bashers point out it can be a quarterstep behind in some vintages, like '96 & '02 & '03, when Medoc typically does better than RB. But the thing I love is that it's often a full step ahead of some of the upper Medoc 1sts in more RB vintages like '98 & '01.

Can I vote for Chateau Palmer?

Someone correct me (is it necessary to say that) if I'm wrong but my understanding of the '55 classification was based on selling price. And it is only logical to assume that Mouton was at the top of the 2nd Growths. So it is only a minor recalibration to move them from 2nd to 1st. The delineation was probably based on something like "Wines selling at $15 and above are 1st, wines selling at $12-$15 are 2nd, wines selling at $10-$12 are 3rd, etc.. So moving from the top of 2nd to the bottom of 1st was merely a matter of political prowess, persistence, and marketing savvy. Everyone else has been content to let the cards fall where they may. It is still (and always will be) one of the great wonders of the "ancient" world. It's just one more thing that makes wine so interesting.