We transpose to fit the needs of the soloist or vocalist. And there are times when the song just sounds better in a specific key. A person who speaks or sings in a range that is to high or to low normally ends up with voice problems. Do not try find a key you sing in, but find the range your voice is comfortable in. They are not the same. Find your singing range (the highest note the low note you sing without straining) then applying that information to the song you wish to sing and that will give you the key you should play the song in.

I feel it is good learning to play the song in different key, this adds to your knowledge and ability to play the instrument. Using the transposing button can be an easy way to go, but it may not be the best way to go. If the key I need is C#, F#, B, or A major, I will use the transpose button. If the original is in the key of C major and I need to go to F# major, I will learn to play the song in G Major. If the song is in C Major and I need to go to Db Major I use the transpose button.

When you transpose a song to far (interval) the Acc. Does not sound as good, it losses something.

My hunble opinions, John C.