What is Your Favorite Key Signature?

[kyjo]

And Lyapunov: Piano Concerto No. 1.

How could I forget this one? Lyapunov's PCs are some of my favorites! Thanks for reminding me of it, Jim :)

[David Carter]

I'm very keen on Bb major because Bb0 (or the note a semitone above the lowest note on the piano) is a most rude note on my tuba.

[Gauk]

E-flat minor, like B-flat minor and D-flat major, is another key favored almost exclusively by the Russian composers ...

Curious, that. I like these "dramatic" keys myself, though I could not say I had one favourite any more than I could say I had one favourite colour.

[autoharp]

E-major is inherently out of tune and unstable, especially on the piano.

Excuse me?  Due to equal temperament, E Major is just as stable and in tune as any other key, especially on the piano!

Only true in theory, Jim. How many really good piano tuners do you know?
Do you really find all 5ths on a piano identical?

[JimL]

E-major is inherently out of tune and unstable, especially on the piano.

Excuse me?  Due to equal temperament, E Major is just as stable and in tune as any other key, especially on the piano!

Only true in theory, Jim. How many really good piano tuners do you know?
Do you really find all 5ths on a piano identical?

You answered your own question.  If the piano is tuned properly, by a trained professional, then all the notes will be equally "in tune" and all the 5th will be identical.  It goes without saying that this doesn't apply if you have a bad piano tuner.  ;D

[Neil McGowan]

  If the piano is tuned properly, by a trained professional, then all the notes will be equally "in tune" and all the 5th will be identical.  It goes without saying that this doesn't apply if you have a bad piano tuner.  ;D

But there is no such thing as one single equal temperament.  There are many different permutations.

12-TET is favoured by some tuners, but the results can be quite unsuccessful with thirds (see above)
There is some more information about 12-TET, and the reasons & places it goes wrong on pianos, here on WikiPedia.  Some of this stuff is specific to pianos and their mechanisms. There is a detailed listing of the mathematically 'correct' frequencies of all 88 notes of a concert grand, but in reality - explanation given there too - these are not always the best choice. So when you ask for 12-TET, in 95% of cases you're still not getting it, but the tuner's corrected version of it instead.

31-TET is used by many professional tuners these days. It tempers the fifths, in order to get the thirds in closer.

There is also 41-TET, which is a decent compromise, but there are still some ropey fifths. The tuners at the Moscow Conservatoire use 41-TET, unless given other instructions, for example. 53-TET is the closest usual tuning to strict Pythagorean, but it drives people bonkers. It's used in Turkish music, though.

Some performers of atonal music go for 72-TET, which is a correcter "mathematical" squeezing. But I don't know any tuners who will put this tuning onto an instrument that is intended for general use - and in fact many would baulk at it entirely.

It's worth remembering that 'just temperament' is not the same as 'equal temperament'. It's also worth remembering that the words 'temper' and 'tamper' have the same root :)

[Maestro267]

I'm a big fan of B minor. A lot of my favourite music I have later found out is in that key. Tchaikovsky used in for two of his symphonies, including his longest, Manfred. It also features prominently in Swan Lake. Other great works in the key include Shostakovich's 6th Symphony, Gliére's 3rd (Il'ya Muromets) and Paderewski's only symphony (Polonia), the latter two of these are both epic works of over 70 minutes' duration.

[ahinton]

I don't have one. Should I?

[oldfezzi]

Eb

[autoharp]

I don't have one. Should I?

As a man who knows his piano music, it wouldn't be C major, would it?

G# minor?