Oddly enough, a Fantasy Sports site I manage at work has a few affiliations with some online sports betting sites, and to be quite honest most of them are pretty shit, and almost all of them look pretty shifty. Even sites we know to be legit and that look legit enough have tons of issues, either with slow payments or shifty bets from certain players etc.
One such one that we've had the least complaints about has been Bovada, but I dunno if they'll accept New York registrations, we affiliate with a lot of sites that refuse registrations from New York, New Jersey, and Delaware and IIRC Bovada is one of them. There's also Sportsbetting.AG or BetOnline.ag as well, but again I'm not sure if they'll take New York registrations.