AO 2012 for sure, simply because I was so convinced she had that title after winning the semis, and it really was a shock for me to see how it unfolded
The manner of the Olympics defeat was painful, but I wasn't actually expecting her to win it (the only time I've actually expected her to lose to Serena in their last few matches
) and I honestly went into the tournament expecting a 3rd-round loss to Lisicki, so it wasn't too bad in the long run, and I was actually quite pleased after the Wimbledon 2011 final, because I also really didn't think she was winning that one and because it was one of the rare occasions where the positives of finally making a final after years of being in the wilderness outweighed the negative of the end result.
Miami final last year was only painful because of who she lost to and the fact her "shade" towards Radwanska ended up blowing up in her face, but if she'd lost that final to Li or Stosur or someone then I wouldn't really have cared much at all tbh
I know some people here really want her to win Miami, but speaking personally, I wouldn't really lose that much sleep if she ended her career without it.