I am sure there are others that compare, but I find it amazing that Mike Hessman has not gotten more of a chance to be a MLB player. Yes, he gives you that home run or nothing at bat, such as the likes of Rob Deer or Pete Incaviglia, and his career minor league average is just .231. His 370 HRs and 1044 RBI have to be among the most ever. Just for the simple reason that players that put up numbers like his 2007 (.254, 31, 101) and 2008 (.271, 34, 72), they get legitimate chance of playing at the MLB level. Not Hessman, which is why he has accumulated such numbers throughout his minor league career. Just as a reminder that he has a power bat, he hit .231, 35, 78 for Oklahoma City of the Pacific Coast League (Astros AAA). If he manages to hit 400 minor league career HRs, it would be an amazing feat. Don't know if he is hanging around Houston's minor league camp, but it might not be a bad place to catch on and get some MLB playing time.
The late Steve Demeter played in the major leagues just briefly during the 1959 and 1960 seasons. Because all stats were not kept from A-AA leagues, some of his career stats are incomplete. Incomplete, where he had much more than was being totaled. Demeter's story has to include passing up opportunities to play in the big leagues. This has never been confirmed. There would be no other explanation for a player to have 7 consecutive solid seasons at the AAA level and not get a call up to the big leagues. Among his official career numbers, he has 2455 career minor league hits, 482 2Bs, 70 3Bs, 272 HRs and a .290 career batting average. Based on the fact of having 5 minor league seasons incomplete because all stats were not kept in all league, Demeter had way more than 814 runs scored, more than 963 RBI and 511 walks to go along with his 783+ strikeouts. Steve passed away February 3rd at age 78.
Val Pascucci has had a similar minor league career. At age 33, he has 251 career HRs, with another full season at AAA likely for 2013. The all time leader in minor league HRs is considered to be Hector Espino. He finished with 484, however, he played just about his entire career in the Mexican League. According to professional baseball, the Mexican Leagues are considered to be AAA.