SO is Sergio Parisse the greatest specialist No 8 ever. I would argue it’s a dead heat between him and Mervyn Davies but as the Italian has sustained his excellence over 17 Test seasons in an often outgunned team I would, if forced into a corner, go with Parisse.
THE OTHER CONTENDERS
Kieran Read (New Zealand):

Two-time World Cup winner with New Zealand and currently on 113 caps. Has all the skills and although he is usually operating on the front foot behind a mighty New Zealand pack, he has often been seen at his very best on those occasions when New Zealand find it tough going up ...