Transposing is bad, but if you are very fluent and comfortable in a certain area then I think sometimes it might be necessary. My favorites in order are: Bb, F, Eb, Ab, and C is okay but it bores me. ( idunno y) If I'm ata church playing and I've never heard the song, then I'd find it easier to figure out the changes in Bb. So i'd transpose. Bb to me is comfortable, not easier, but physically, with my hand size it feels the best. But given time to learn a song, I'd learn it in the written key, I like to hop off the keys and re-vamp a song on the organ. Basically, transpose to me, is for emergency purposes only. But...I know...it's still bad. lol