Sting's "workrate" legacy is hurt by three factors:
1) When his main event opponents were good (early 90s WCW) the promotion wasn't big so the matches aren't held in the same regard. Vader, Luger, Rude, Flair, Muta, etc.
2) When the promotion was big (late 90s WCW) the main eventers he got were a pretty mixed bag. Hogan, drunk Scott Hall, Kevin Nash, Goldberg, old Flair, old Luger, etc. His one "big" match from a work rate perspective would have been Bret Hart, but Sting was checked out because of personal problems and ready to go home and Bret Hart was pretty much checked out as well. Wasn't a bad match, but wasn't impressive.
3) Nothing he did in TNA really counts and he was old anyway.
It is not Sting's fault that WCW didn't move good workers into the main QUOTE]
First, you cant say "TNA doesn't count" since they are watched by somewhere around 2 million people every week at the height when Sting was there. And Sting had some terrific matches with Kurt Angle, Abyss, Samao Joe while there. He was EXTREMELY OVER during that time too.
Second, if you criticize "early 90s" WCW then you have to discount most of Taker's career pre 1999 as well. In the early 90s both companies were way down, by 1993 WCW was actually very close to WWE domestically and by 1995 WCW was routinely matching or beating WWE ratings, very close in PPV buys, and arena attendance, and a year later WWE was clearly the #2 company in the US. Just as Sting was a major player in that time, Taker was a major player in WWE at that time, a time of lost viewers, decreased revenues, and their losing position as the #1 US Company.
Most of Taker's career pre 1998 he was usually a second tier guy, who occasionally worked in the main events. In the early 90s he was very new on the scene so I wont knock him for taking a back seat to Hogan, Flair, Savage, and Brett Hart in WWE at that time, but he was bypassed into the top tier by Scott Hall, Razor Ramoan, and Shawn Michaels 93-96, mostly staying in mid card fueds save for an occasional run vs Brett or Sid. Sting was the # 1 face in WCW this entire time, and almost exclusively wrestled in the top 2 matches on the card the entire time. Even the arrival of Flair, Hogan, & Savage didn't bump Sting into the mid card, it simply gave him new people to work with in the top tier.
Taker very slowly built a nice career, mostly as a gimmick player and mid carder, but when given a chance to shine during the latter half of the Attitude Era he connected with fans and did well. Still, for most of the 90s Sting was more prominently featured and a bigger star.
I do think Taker was better in the ring, one of the best for his size all time. That doesn't change the fact that he was mostly a second tier player while Sting was main eventing. Arn Anderson is a HOF worthy talent but he was mostly a second tier guy, over enough to get top teir runs or have credibility teamed with top tier talent on occasion but he wasn't a consistent main event level star. He was over though, he was good. So was Taker.
The difference between them is not so cut & dry.