The private lines were managed by several companies under the supervision of NYCDOT. They were hit or miss depending on who was handling what. Queens Surface, Triboro Coach, Jamaica Buses and Green Lines were all in Queens, Brooklyn had Command and Manhattan/Bronx had New York Bus Service and Liberty Lines. They were all once separate but most of them were eventually controlled by larger private entities. To be honest, Green Lines, Triboro and Jamaica had some of the most raggedy-looking buses growing up. Queens Surface and Command were pretty good with their maintenance. Never spent much time in Manhattan and Bronx as a kid but NYBS and Liberty Lines' equipment also looked pretty decent to me.