OPS+ is a pretty good shorthand for comparing the careers of hitters from different eras. I wouldn't say it's perfect and I actually think it punishes hitters who played in explosive offensive eras a tad too much and ranks older era hitters too highly (easier to dominate when there's less skilled players around) but it's a pretty good measurement as far as these things go.

#1 Babe Ruth (207)

The house that Ruth built is being destroyed at the end of this season and many of his greatest single season records have been destroyed by Barry Bonds. But he still holds some of the most impressive career hitting records such as the career OPS, career slugging percentage, and as obvious by his #1 ranking here, career OPS+.

#2 Ted Williams (191)

Williams is the career leader in on base percentage and is still seen by many as the greatest pure hitter of all time.

#3 Barry Bonds (182)

Barry Bonds' stretch from 2001 to 2004 is probably the most dominating any hitter has ever been in any 4 year period in major league history. The argument that he had an unfair advantage over his competitors due to possible use of steroids/HGH is now quite thin as it's obvious that use of performing enhancing drugs has been the norm (and not the exception) in baseball for a long time. Bonds' 762 home runs may be his most famous record but I think it's far from his most impressive. I'd take his .609 OBP in 2004 or his .863 SLG in 2001 over that and I think both of those records will last longer than his career home run record.

#4 Lou Gehrig (179)

Gehrig is somewhat overshadowed by his teammate Babe Ruth and the disease that ended his career & his life and was later named after him. But he was an incredible hitter in his own right who probably doesn't get the accolades he deserves as one of the greatest hitters in MLB history.

#5 Rogers Hornsby (175)

Hornsby Vs. Cobb is a good argument that I think can reasonably go either way. By OPS+ Hornsby comes out on top.

#6 Mickey Mantle (172)

Imagine if he had laid off the sauce and stayed healthy?

#7 Joe Jackson (170)

Imagine if the scandal in 1919 had never gone down. He looked to be well on his way to one of the most impressive careers in baseball history. Even though his career ended way too early at age 30 in 1920 due to the scandal of the previous year's World Series he still did enough during his career to be considered one of the all time great hitters.

#8 Ty Cobb (167)

You could make the argument that Cobb has got more than his fair share of the attention when compared to Rogers Hornsby, Lou Gehrig, and Jimmie Fox. But Cobb was a special player who will always stand out in baseball history.

#8 Albert Pujols (167)

With the Bonds era now over (apparently?) Pujols is now the best hitter in baseball. He's only 28 years old and will likely go down as one of baseball's all time greats. And yes he's far better than Alex Rodriguez who as you'll notice, is not on this list (it would have to be a top 40 list for him to be included, by the way.)

#10 Jimmie Foxx (163)

Foxx is often overlooked when looking at the greatest hitters in early baseball history. That may be because his career started to fade at age 32. If he had kept his earlier pace for a few more years he would be a much more towering figure in baseball's career leaders. Foxx had some of the best seasons of his era. In 1932 he hit .364 with 58 home runs (nearly tying Ruth's then record of 60 which was only 5 years old at the time.)

MIA?

Who did you expect to see in this list but isn't here?

Willie Mays? His 156 mark wasn't enough for the top 10. Some of Mays most impressive skills (baserunning & defense) are of course not included in the OPS+ calculations which is purely a measurement of hitting skill.

Hank Aaron? Aaron's greatest asset was his consistency over the course of a long career. He was never as dominating as any of the hitters on the top 10 list. His career OPS+ was 155.

Alex Rodriguez? His 147 mark wasn't close to being in the top 10. Rodriguez's skills as a hitter have been somewhat exagerated due to him starting his career as a Shortstop. But of course OPS+ looks at hitting stats purely without looking at it through the lens of expected performance by position.

***I left Dan Brouthers (170) off the list as I don't think it makes sense to compare pre-1900s players to those in the "modern era."