Hart just ahead of Richo, mainly because Hart was a much shorter player who had to rely much more on natural ability and athleticism. And I had #4 on my duffle coat. 
Agreed Smokey, the thing I reckon people forget was that Richo was not a great contests mark when he first joined the AFL.
He was all arms and legs, great athleticism which he relied on heavily to have an impact.
I remember Archer absolutely smashing him to bits by just niggling and smashing into him every time there was a contest.
After the knee, he came back stronger and began to better judge the ball in flight while also having the strength and confidence to hold his position.
I remember a game against the roos late in his career where he took something like 20 grabs and about half of those were contested.
It was the best marking performance (along with Carey in the mud vs power in a final at the G) I have ever seen.
People talk about how much he relied on his natural athletic gift but the development of his contested marking was phenomenal
