I always wanted to do a top 10 of synthesizer solos in Jazz/Fusion/Soul. Although the list is not strictly limited to this type of music, most of them are Jazzy/Improvised style anyway. If you have any remarks or other suggestions please let me know. This is my list:
1) Michael Brecker/Steps Ahead - In a sentimental mood
Synth: Oberheim Xpander driven by EWI
Great improvisation by Michael Brecker on EWI. Very expressive synth sound controlled by breath and usage of large note range through octave rollers on the EWI. You can also hear Mike Mainieri on Memorymoog.
2) Herbie Hancock/Chaka Khan - And the melody still lingers on/A night in Tunesia
Synth: Clavitar driving Sequential Circuits Prophet 5 rev 2
Nice screaming lead sound played on a remote keyboard called the Clavitar.
6) John Mclaughlin/Mahavishnu Orchestra - Clarendon Hills
Synth: Proton guitar synth
Typical fast-riff McLaughlin style solo.
Note: by no means are the above samples intended to violate any copyrights, it just serves to demonstrate (a part of) the particular synthesizer solo. If you want to support the artist, you can click the iTunes link to buy the song or buy the complete album of the artist which I strongly recommend if you don't own the music already.