My favorites are Metropolitan Plant Exchange in Fort Lee and Willow Run in Cresskill. I particularly like Willow Run for shrubs because they carry small ones at low prices. They carry larger sizes too but I prefer the small ones because they're easier to carry and if they don't do well in my garden, I haven't lost a lot of money.
I like Eisele's in Paramus (intersection of Pascack Road and Oradell Ave.) I could live there. But if you want specimen trees and plants, and generally excellent stock (from annuals to perennials), try Rohsler's in Allendale. Pricey, but the trip up can be scenic and the time there well spent. But I have to say, I've never had luck with The Metropolitan Plant Exchange, at least the one in Paramus - neither live plants nor cut flowers.
Metropolitan Plant Exchange (Fort Lee, Paramus, W. Orange) Good for exotics and winter hardy. Strawberry's (Wayne) Great selection on hardy and tropicals DiPiero's (Montvale)Decent collection Corrado's (Clifton) Good for winter hardy plants, Home Depots D'Angelo's (Dumont) Especially good for winter hardy plants Willow Run (Cresskill), also winter hardy specialists