Historically, Pete has been slightly more dominant on serve than Federer at Wimbledon, though Federer I think holds the record between the two of conceding the least BP's over the course of the tournament.
Federer is superior to Sampras off the ground on the grass whether it be forehand or backhand drives or slices. Sampras is superior at the net and when he wants to equals Federer's return ability on the surface, though he put less into return games generally probably than Federer did.
Here are some statistics that were compiled by NYCTennisFan over at the other forum.
''Some serve stats of the past 18 Wimbledon champions. The break chances stat can be a bit misleading because someone can get down 15-40, save the break points, only to get broken after the opponent takes the AD, hence having more break points against because you were saving them in the first place. Then again, why in the hell are you getting down 0-40 Pete or Goran? . In any case, here are the stats. Nobody dominated the 1st serve points won like Sampras. Federer has done extremely well on his second serve. Only Stich, Hewitt and Agassi in the past 15 years have been broken in the double digits.
PLAYER.....YEAR....# of GAMES SERVED...BP WON AGAINST....1st serve pts won...2nd serve points won....1st serve %...tot. % GAMES HELD...tot. % of service points won
Michael Stich....1991...132...11/45...80.3%...58.6%...56.2%...91.7%....70.8%
Andre Agassi.....1992...132...17/50...73.1%....51.7%..61.2%...87.7%....64.8%
Pete Sampras....1993...123...5/22.....85.9%....49.8%..66.9%..95.9%....73.9%
Pete Sampras....1994...106...2/22....89.8%.....55.3%..64.3%...98.1%...77.5%
Pete Sampras....1995...132...8/35.....87.3%.....53%....61.1%...93.9%...73.9%
Richard Krajicek..1996...110...6/30.....88.3%....52.7%..64.5%...91.8%...75.7%
Pete Sampras.....1997...118...2/19.....89.4%.....56%...70.4%...98.3%...79.5%
Pete Sampras.....1998...121...6/32.....89.1%....53.8%..57.7%...95%.....74.2%
Pete Sampras.....1999...101...5/18.....89.7%....50.2%..63.8%...95%.....75.4%
Pete Sampras.....2000...123...5/29.....82.7%....57.3%...65.1%...95.9%..73.8%
Goran Ivanisevic..2001...147...9/27.....85.7%....54.3%...60%.....93.9%...73.1%
Lleyton Hewitt....2002....107....11/41...78.2%....59.6%...54%....89.7%...69.6%
Roger Federer.....2003...105....8/30.....77.9%....59.3%...61.4%..92.4%...70.4%
Roger Federer.....2004...108....6/33.....77.1%....62.1%...67.2....94.4%....72.2%
Roger Federer.....2005....111....7/16.....80%......63%....64.8%...93.7%...74.0%
Roger Federer.....2006....100....4/12.....79.5%.....64%....66.5%...96%....74.3%
Roger Federer.....2007....102....7/24.....78.0%.....61%....65.1%...93%....72.1%
Rafael Nadal........2008....123....5/23.....77.7%.....62%....72.4%...96%....73.4%
Roger Federer.....2009....135....5/19.....87.5%.....61%....66.9%...96.3%..78.7%
Rafael Nadal........2010....124....7/23.....79.0%.....61.9%..68.1%...94.4%..73.6%
Novak Djokovic....2011....107...11/28...77.4%.....59%....68.5%...89.7%...71.6%
Roger Federer.....2012....133....9/31.....78.0%.....58.5%...67.3%...93.2%..72.1%
Ranked by Total % of serve points won
Pete Sampras......1997.........79.51%
Roger Federer.....2009.........78.73%
Pete Sampras......1994.........77.48%
Richard Krajicek...1996.........75.66%
Pete Sampras......1999.........75.40%
Roger Federer.....2006.........74.30%
Pete Sampras......1998.........74.17%
Roger Federer.....2005.........74.02%
Pete Sampras......1995.........73.96%
Pete Sampras......1993.........73.95%
Pete Sampras......2000.........73.84%
Rafael Nadal........2010..........73.6%
Rafael Nadal........2008..........73.37%
Goran Ivanisevic...2001.........73.14%
Roger Federer......2004.........72.18%
Roger Federer.....2007..........72.07%
Roger Federer.....2012.........72.04%
Novak Djokovic....2011........71.6%
Michael Stich......1991..........70.80%
Roger Federer.....2003.........70.72%
Lleyton Hewitt.....2002.........69.64%
Andre Agassi.......1992.........64.80%
Ranked by % of first serve points won
Pete Sampras......1994.....89.8%
Pete Sampras......1999.....89.7%
Pete Sampras......1997.....89.4%
Pete Sampras......1998.....89.1%
Richard Krajicek...1996.....88.3%
Roger Federer......2009.....87.5%
Pete Sampras......1995.....87.3%
Pete Sampras......1993.....85.9%
Goran Ivanisevic..2001.....85.7%
Pete Sampras......2000.....82.7%
Michael Stich........1991......80.3%
Roger Federer......2005.....80.0%
Roger Federer......2006.....79.5%
Rafael Nadal........2010......79.0%
Lleyton Hewitt......2002.....78.2%
Roger Federer......2007.....78.0%
Roger Federer......2012......78.0%
Roger Federer.....2003......77.9%
Rafael Nadal........2008.......77.7%
Novak Djokovic....2011......77.4%
Roger Federer.....2004......77.1%
Andre Agassi.......1992......73.1%
Ranked by % of second serve points won
Roger Federer.....2006......64.0%
Roger Federer.....2005......63.0%
Roger Federer.....2004......62.1%
Rafael Nadal.......2008......62.0%
Rafael Nadal.......2010.......61.9%
Roger Federer.....2007......61.0%
Roger Federer.....2009......61.0%
Lleyton Hewitt....2002.......59.6%
Roger Federer.....2003......59.4%
Novak Djokovic....2011......59.0%
Michael Stich........1991.......58.6%
Roger Federer.....2012........58.5%
Pete Sampras.....2000.......57.3%
Pete Sampras.....1997.......56.0%
Pete Sampras.....1994.......55.3%
Goran Ivanisevic..2001......54.3%
Pete Sampras.....1998.......53.8%
Pete Sampras....1995.......53.0%
Richard Krajicek..1996......52.7%
Pete Sampras.....1999......50.2%
Andre Agassi.....1992.......51.7%
Pete Sampras....1993.......49.8%
Ranked by total % of service games held
Pete Sampras.....1997......98.3%
Pete Sampras....1994.......98.1%
Roger Federer.....2009......96.3%
Roger Federer.....2006......96.0%
Rafael Nadal.......2008......96.0%
Pete Sampras.....2000......95.9%
Pete Sampras....1993.......95.9%
Pete Sampras.....1998......95.0%
Pete Sampras.....1999......95.0%
Roger Federer.....2004......94.4%
Rafael Nadal.......2010.......94.4%
Pete Sampras....1995.......93.9%
Goran Ivanisevic..2001......93.9%
Roger Federer.....2005......93.7%
Roger Federer.....2012......93.3%
Roger Federer.....2007......93.0%
Roger Federer.....2003......92.4%
Richard Krajicek..1996......91.8%
Michael Stich.......1991.........91.7%
Lleyton Hewitt.....2002.......89.7%
Novak Djokovic...2011.......89.7%
Andre Agassi.......1992.......87.7%
Ranked by fewest amount of times serve was broken
Pete Sampras......1994.............2
Pete Sampras......1997.............2
Roger Federer......2006.............4
Pete Sampras......1993.............5
Pete Sampras......1999.............5
Pete Sampras......2000.............5
Rafael Nadal........2008.............5
Roger Federer......2009.............5
Richard Krajicek....1996.............6
Pete Sampras......1998.............6
Roger Federer......2004.............6
Roger Federer......2005............7
Roger Federer......2007............7
Rafael Nadal........2010.............7
Pete Sampras......1995............8
Roger Federer......2003............8
Goran Ivanisevic...2001............9
Roger Federer......2012............9
Lleyton Hewitt.....2002.............11
Michael Stich......1991..............11
Novak Djokovic.....2011.............11
Andre Agassi.......1992..............17
Ranked by fewest amount of break points allowed
Roger Federer.....2006...................12
Roger Federer.....2005...................16
Pete Sampras.....1999...................18
Pete Sampras.....1997...................19
Roger Federer.....2009...................19
Pete Sampras....1993....................22
Pete Sampras....1994....................22
Rafael Nadal.......2008...................23
Rafael Nadal........2010..................23
Roger Federer.....2007...................24
Goran Ivanisevic..2001..................27
Novak Djokovic....2011..................28
Pete Sampras.....2000...................29
Richard Krajicek..1996...................30
Roger Federer.....2003...................30
Roger Federer.....2012...................31
Pete Sampras.....1998...................32
Roger Federer.....2004...................33
Pete Sampras....1995....................35
Lleyton Hewitt....2002...................41
Michael Stich....1991.....................45
Andre Agassi.....1992....................50
Hewitt and Federer use the return of service a lot more than Sampras, Becker, Krajicek, Goran, etc. of the mid 90's since the speed of the court has been slowed down and the returner has more of a chance. Hewitt and Federer served a lot less than everyone else except Sampras of '94 since he was breaking and holding serve. Sampras of 1999 had a retirement by Flip. Had Flip not retired, Sampras probably would've come close to 120 serve games for that year as well.
***A note about Pete's dominance on serve. He had a record of 58-2 from 1992-2000 where he was a SF, W, W, W, QF, W, W, W, W.
In those 60 matches, he had 11 matches where he didn't face a break point at all, and had 31 matches in all where he wasn't broken. That's about 52% of his matches in that run where he wasn't even broken. ''