My placing
What struck me, even back when he was playing was, how he was really good on all surfaces. His eye and timing was extraordinary. I really first thought he was a world beater when I saw him thump Becker and Edberg in the WTF on indoor carpet in 1990 - particularly his demolition of Becker - who is one of the all time indoor greats. He had added a lot of weight to his service between the US Open and the WTF. We all could see on Medium and Slow surfaces how good he was - but this was a revelation. Then he went all the way at Wimbledon in 1992 and its superfast grass then - repelling servers like Becker and Ivanisevic. Just amazing.
I don't know where to place Agassi in the all time discussions. But in the Open era I would put him 9th behind - Federer, Nadal, Lendl, Sampras, McEnroe, Borg, Connors, Djokovic. Djokovic only past Agassi this year in IMHO when he won Wimbledon over Federer - and then only by a small margin.