When you look at body of work, she certainly has a solid case for it. The major criticism I have when you look at her W career is that it seems to be her teams are all or nothing....they're either a consensus top team in the league that wins it all, or they're mediocre and underperform.
DT didn't make the playoffs until her 4th year when she had Pondexter and Taylor. The next year they inexplicably don't make the playoffs, and then win it all again the following year.
The next two years (2010 and 2011) Phoenix underperformed and went 15-19 and 19-15 with a loaded roster.
In 2012 DT was out most of the year and the team was heavily suspected of tanking in an effort to get Griner. It worked, and in 2013 they will still mediocre going 19-15.
2014 they put it all together with one of the best seasons in league history, and in 2015 DT was out, but they still finished 20-14 and 2nd in the west. DT comes back in 2016, and the team is inexplicably worse, finishing 16-18 with Griner and DT. This year they're 7-6, which is again underperforming for the level of talent they have. That said, in the moments when the spotlights are shining brightest, DT delivers as well as anyone ever has...and I think that's one of the biggest arguments for her being the GOAT.
Compare that to Maya Moore's W career where she has won 3 titles and played in 5 Finals in 6 years. Her teams have had the best record in the league for 6 of the 7 years, and the 7th year they were 2nd best. She's never had less than 20 wins in a season. DT has only cracked 20 in 3 of her 11 (or 12) seasons.
Maya's teams have always lived up to expectations and again appear to be the favorite for the title.
She has had a very strong supporting cast (arguably as strong or stronger than many of the Phoenix teams), but her level of consistent greatness is matched by no one. If Minnesota goes on to win it all this year, she'll have more titles than DT, twice as many title appearances and have accomplished this while playing in about 1/2 as many seasons. If you compare their college years, you can make an argument for both but I'd have a hard time voting against Maya when she was a 3x POY, 4x 1st team AA, 2 time undefeated champion and owns many statistical records at Connecticut. At worst, you'd have to call it a draw comparing the two. In regards to team USA success, you can argue Taurasi has the edge here, but I believe Moore equals Diana when it's all said and done. Team USA success has less validity than it used to considering how dominant the women's program has become. USA hasn't lost in the Olympics in 25 years....it's like varsity playing JV. The tougher/more career defining games for both have been in the pros and collegiate level.
You can make an argument for both, but at this point I'd put Maya above Taurasi when you look at results and her consistent excellence.