Is this based on quality or results? I think Hingis/Kournikova are certainly one of the better doubles teams of all-time, but they only won 2 majors (only played about 4). I can't place them in the top 5 all-time when there are many teams with more majors than that.
I think the players in my mind were already mentioned above..EXCEPT one. Of course I might be a little biased but I think Arantxa deserves an honorable mention. Sure she wasn't thought of as a doubles specialist but in all minds she had the results to back her up. In her career she has reached #1 in the world in doubles, has won 67 career doubles titles (with numerous partners) which includes 6 Grand Slams, and she has also won 4 mixed doubles titles as well.