The Ninja has no place in a "best" party. Not when the Scout is available.
The Spellthief is only as good as the buffs he can reliably steal -- when together with a Warlock and Dragonfire Adept, he can be pretty darn good, depending on their Invocation selection.
For the parties I've written here, I try to keep them all at the same "renewal rate". Some parties can do their thing all day (Binder / Warblade / Warlock), while others can pull out some big guns a few times a day (Barbarian / Psion / Cleric) and then would like to rest for a while.
C, -- N