lets see...
lennon/harison - gobsmaking melding of talent
slash/izzy - ditto (but not quite as good)
richards/wood - "me and woody don't know who played the last lick, its as close as that" - richards
o brian/greenwood - listen to the bridges of paranoid android and the chorus of creep to see how these two meld together seamlessly
felder/walsh - what do you mean you've never heard the solo from hotel california?
i'll be back if i think of more
Tandem Felix