TOS: it has to be Spock and McCoy
Next Gen: well everyone loves Picard, upon repeated viewings i have grown more and more fond of Riker.. and of course Worf and Data are great. I coul never stand Troi - total waste of time.
DS9: I like Jadzia and Odo..
Voyager: Seven and the Doctor but all of the characters I liked (even Neelix who i think is much maligned). Though was never keen on Kes, she was a bit "wet" though.
Enterprise: Trip and Dr Phlox