How can bitcoinrush be a A- book when they recently banned all US players?
Which makes up a large # of their players, so I bet their investors are thrilled with that move.

Along with them purchasing Money Pot, who owes many, many investors hundreds of Bitcoin and they are now in a law suit.

Maybe they would be a A- book if:

They allowed 1st half and 2nd half betting, which they dont
They allowed multi-sport parlays, which they dont.
They offered more than 9 sports to bet on, which they dont.

Shall I go on?

Just because they have been around the longest, doesnt make them a good book.