I vote for Enzo - certainly less daily driveable, more head turner, but more event driver...
SL beautiful but dropping in value, 599 GTB also beautiful and seriously great V12 - (have a soft spot for the V12 - so few around and great sound)...
BUT why sell and trade up...If space is your constraint, build more...I tend to sell when I;m bored - you should only sell if you need a change, with less than 1000 on the SL has anyone really enjoyed it enough?