Hot Take: Steffi had a greater career than Serena
Most people have Serena as the Women GOAT but I think Steffi has a bigger claim especially as a Singles-Players.
In terms of Slams yes Serena had the edge with 1 more Slam but Steffi retired at 30 while Serena did at 40 which makes Steffi the more dominant player at her peak since Serena needed 10 more years to catch up to her. And it's not like Serena had some crazy competition, her biggest rivals were the likes of Venus and Sharapova who wouldn't really do much vs Steffi.
However, I think the extra slams doesn't compensate the massive gap in actual career titles, Serena won 72 Trophies while Steffi won 107 Trophies, I think a career with 107 Trophies with 22 Slams is better than 72 Trophies with 23 Slams
Now, there are other areas where Steffi has the lead such as her having the Golden Slam which is arguably the greatest achivement in tennis History, winning the Calendar Slam is already hard but winning the Olympics is arguably the best achivement in tennis history and this would include the Big 3 as well.
Steffi also has other things above Serena such as a greater win ratio in both slams and overall career, overall career is 88% vs 85% and in Slams is 89% vs 86%. On top of this, he has more worlds as world number 1 as 377 which is second only to Djokovic in tennis history and over 50 more weeks than Serena and Steffi finished world number 1 8 times while Serena did 5 times
So, while Serena has one extra Slams I think Steffi edges it out with 30 more trophies, a much more dominant peak, the golden slam, higher win ratio and more world number 1 weeks
So just to compare
Slams: Serena
Titles: Steffi
Win Ratio: Steffi
Year Ending World Number 1: Steffi
World Number 1 Weeks: Steffi
Calendar Slam: Steffi
Golden Slam: Steffi