The Sharapova vs. Henin AO 2008 QF was the first thing to come to mind as a flawless performance and perhaps my all-time-favourite match! Henin, as the world No.1 at the time and 7-time GS Champ, with a 32-match winning streak before this QF and as competitive as ever, throwing everything at Sharapova - and Sharapova dominating anyway. The score doesn't do this match any justice. I would rank it even higher than the Wimbledon 2004 final.
I would add honourable mentions - the Indian Wells 2013 final against Wozniacki, the Montreal 2018 2R match against Kasatkina, the AO 2019 1R match against Dart, etc.
Those choices for #5 and #4 are quite strange. You could have picked others from the AO 2008 alone. Davenport, Dementieva, Jankovic. On the top of my head, AO 2013 against Venus, Wimbledon 2011 against Cibulkova, and that double bagel at the French the year she won where her opponent didn't get to hit a single winner. But I do appreciate the content.
What i loved about her matches was that she could win it after nearly losing or lose it after almost winning...but she usually won in the end somehow. That's a unique quality...her matches have always been streaky, topsy turvy, brutal, crazy marathons, her serve can be excellent or she'll hit a double fault...so satisfying to see her play at top level...the girls she met on court played her with no mercy bc they received none from Maria. They just threw everything at her which made her fight even harder til the end. 😍😍😍
Well, even Serena tanked/retired from some matches she was clearly losing. However, I don't recall Sharapova ever retiring from a match to prevent a bagel or a breadstick - no wonder it was one of her bugbears when her opponents claimed to be "extremely injured". 😆
A reminder... shrapova admitted to doping thru all these matches.. so all this grit and effort are aided and enhances that she had an advantage other players did not..