Stake is good for me for nfl and parlays
Nitro is legit and wont jack you
Never played with sportsbet but they have a big following, really dont think they do the kyc
All the sportsbooks you've mentioned are good based on my experience.
My first sportsbook was Nitrogensports, then sportsbet, and stake., I'm actively playing with these two sites along with some of my favorites, and thus far, I'm never bothered by any KYC requirement even though I won a decent amount sometimes.
On the other hand, there are some bad reviews about nitrogensports if you'll look at their trust rating. That has lessened their popularity but before, they're really popular.
As long as you do good and there's no other thing that you do that violates them with your account, you're up and nothing to worry about such.