Rogie or Sampras?
Sampras: 10 career grass titles (1 Manchester, 2 Queen's Club, and 7 Wimbledons), tied with Rogie for most career Wimbledon finals with 7, 101-20 career record on grass.
Rogie: Record of 11 career grass titles (5 Halle and 6 Wimbledons), tied with Sampras for most career Wimbledon finals with 7, has the record for most consecutive Wimbledon finals with 7 (2003-2009), from 2003-2008 won a record 65 straight matches on grass until losing to Rafa in the 2008 Wimbledon F, 72-1 (98.6%) on grass from 2003-2009 (only 16-11 from 1999-2002), and a career record of 88-12 on grass. Needs to do better than 13-8 to surpass Sampras overall on grass, just another 14 wins to have 102 career wins on grass.
I think Rogie's the greatest ever on grass, but it's still left to be determined if Rafa's the best ever on clay because of Bjorn Borg and Guillermo Vilas. However, when it's said and done, Rogie will be "The King Of Grass" and Rafa will be "The King Of Clay". You can say Rafa's feats are harder because with more matches to play there are more chances to lose, but for Rogie there's only about 4-5 weeks per year of grass tournaments, so he gets such few chances to play grass every year, so his feat is amazing too.
Lastly, on a side note: If Rogie wins 1 more AO, 2 more W, and 1 more USO, he'll have the most of 3 of the 4 grand slams in the open era. To me that's an amazing feat. (Tied with Agassi with 4 AO, one behind Sampras with 6 W, and tied with Sampras and Connors with 5 USO). As for FO, Rafa and Borg will top that list, Borg has 6 and Rafa currently has 4.
Wtf does this have to do with grass dominance?