This is a lot of work you did, and I admittedly didn't bother to look into a comparison of AskGamblers totals for both sportsbooks. If you are using this as a metric, then obviously Sportsbet comes out favorably here, as they only have 4 complaints, 3 of which were resolved.
Then again AskGamblers seems like they are refusing some complaints against SP, like Neymar's.
I'm not rushing to conclusions on why, but it's a fact.