Unsurprisingly, David Ortiz is currently the leading vote-getter for the designated hitter position for the 2013 All-Star Game. Ortiz has played in every All-Star Game since 2004 (winning the Home Run Derby in 2010), with the exception of 2009 when he didn't hit his first home run of the season until May 22nd - he managed to hit 28 homers that season, but most of them came in the second half.
That season aside, it's no secret that David Ortiz is one of the greatest designated hitters to ever play the position, especially since so few players really make a career of it. For many teams the DH spot is a great place to stick your aging players to lengthen their careers, and a convenient way for those recovering from injury to ease back into playing every day - but not for the Red Sox, not since Big Papi came onto the scene in 2003.
Of course, 2004 was the year that David Ortiz earned that nickname and his legendary status, "The Greatest Clutch Hitter in the History of the Boston Red Sox," and neither he nor the Red Sox have looked back. Even Sports Illustrated recognizes Ortiz's special status in a special postion: in their June 24th issue, they ran an excellent article entitled "In Praise [Ducking] of the DH," (paywall at the link) and though it was largely the story of the first DH, Ron Blomberg, the cover photo is a collage of notable designated hitters.
It's no mistake that Ortiz is the central and largest player in that group, despite playing forty years after the first DH stepped into the batter's box. Big Papi is portrayed even slightly larger than Edgar Martinez, a man so talented at the position that the Outstanding Designated Hitter trophy was renamed after him. There aren't many people you want to see at the plate more than David Ortiz with the game on the line, and his prowess is so renowned that the phrase "designated hitter" is basically synonymous with one man: he's leading the All-Star Game voting for the AL DH by a large margin, and will likely be starting in New York next month.