I'm a classically trained pianist. So I'm biased.

IMHO there is nothing to beat a good piano....

Except maybe a well sorted Hammond

Or something huge with pipes played by someone who can play the feet as well as the hands...

However, as a gigging musician my favoured options all have problems. Lets start with size and weight! Therefore I'm going around with a PSR2k. I set this up at home too. To create a "tune" that can be sung along to, or easily recognised, then the keyboard is much better. I do not play Beethoven sonatas on my PSR but I can't play Bossa Nova on a piano (not with the right atnosphere or feel, anyhow).

If I had to choose it would have to be a piano. But can I keep the keyboard on top just in case?