Big aeroplane: The Fokker 100 - a delight to pole by hand, yet with systems and automatics that put its Toulousean antecedents to shame. And the Boeings don't even get close.
Littler aeroplane: The de Havilland Dove 8 - again, smashing fun to pilot, and with such character (NB: fond remarks DO NOT apply to engine-out approaches - either in their frequency of unintentional occurrence or the handling qualities of the aeroplane). The BN2 is also a laugh, but has so many downfalls that I can't quite bring myself to list it as a favourite.
Little aeroplane: Toss-up between the DHC1 Chipmunk and the Grumman AA5A. Both huge fun to fly and teach in.