Dualclassing and Multiclassing brings a whole new dimension to the playing field, and it is for that reason that I usually prefer to leave them out of contention.
Like it or not, it is just not fair to compare a pureclass to a non-pureclass, as non-pureclasses are the combination of two or more pureclasses, giving it a huge advantage over the pureclasses. Factors like slower XP gain and limited levels go flying straight out of the window since we are soloing, and benefits are minimal after level 20 or so.
Since you asked though, in no particular order( and assuming ToB is installed),
- Cleric/Ranger
- Kensai->Mage
- Kensai->Thief
- Wizard Slayer->Thief
- Berserker->Mage( or Cleric)
- Swashbuckler->Mage
- Fighter/Thief/Mage
- Fighter/Mage
- Fighter/Druid
- Fighter->Druid( good luck rolling
)