I've seen some payouts at Robigo Mines of over Cr 4 million, and occasionally over Cr 5 million; but these tend to dry up on repeated visits. Today's visit was more about Grade 5 mats than money, but they too got scarcer after a couple of loops. Hauser's Reach may be more consistent, but payouts don't hit the same peak - though of course you can use a larger ship for more cabins to make up for the lower payouts.
OK, so this is embarrassing. I'd swear I'd seen this pattern on earlier visits, and that I was seeing it again today. But today I was choosing mats wherever possible, so this must have distorted my perception of the figures.
Checking the figures in EDDiscovery, which ignores material rewards when listing mission payouts:
Robigo Mines (Python, six cabins - I like to have shields when I'm carrying passengers):
Run 1: Cr 18,912,050
Run 2: Cr 18,591,800
Run 3: Cr 18,762,600
Run 4: Cr 19,018,800
Run 5: Cr 18,250,200
Hauser's Reach (Anaconda, nine cabins):
Run 1: Cr 22,358,050
Run 2: Cr 20,285,100
Run 3: Cr 18,768,550
Run 4: Cr 20,714,100
Run 5: Cr 17,359,450
There's no obvious decline at Robigo Mines, and while at Hauser's Reach the first payout is noticably higher than the fifth, I'm not sure how significant that is.
It looks from these figures that Hauser's Reach is the more profitable of the two runs:
Robigo Mines avg: Cr 18,707,090
Hauser's Reach avg: Cr 19,897,090
But I calculate that it took me 1.26 times as long to do a run from Hauser's Reach. So in the time I'd take to get the Hauser's Reach average, I'd be making an average of Cr 23,570,933 from Robigo Mines.
Robigo Mines wins.
You're probably more efficient than I am, but then you'd be more efficient at both sites, so the end result would probably be similar.
I trust this is adequate punishment for my error: I've had to fire up Microsoft Excel. Oh, the misery!