No 21st century artist has sold more than Taylor and no artist has sustained their career like this.
Yes, Adele had a bigger peak but she couldn't manage or build up on it. Drake can't tour like Taylor and the quality of his albums is also going down. Rihanna has more hits but she couldn't sell albums like Taylor.
Taylor has been dominating in all fields, whether it is acclaim or sales or tour, and on top of that has a massive fanbase.