"It all comes down to the odds offered primarily in my opinion. If one site consistently offers better odds when compared to the competition, they will definitely attract more punters in the long-term. "

I think the choice of bet too

For exemple

Nitrogensport and Stake for many user are the reference but when you bet on live you dont have all bet on over on soccer for example.
You can find many other match to bet on with good odds on Betnomi.
I have already say on thing , the only site who propose this amazing choice is 1XBIT but for many its a scam.
Choice + good odds ( prematch and on live ) is necessary to be the best sportbook