Is there a difference between Chinatown bus services?

Can anyone who has more experience riding one of the several bus services that start at a Chinatown in one city and end in another tell me if one is decisively better. I have only taken New Century Travel. I first took it to Philadelphia, as it was one of two bus services that go there and the only one that had a schedule amenable to my own. It was very prompt (actually, it even left early!); however, the time that the bus left was such that we were delayed by an hour and a half or so because of awful D.C. rush hour traffic. The bus ride from Philadelphia back to D.C. was on a Sunday afternoon and encountered no problems. When I went to New York a couple months later, I stuck with New Century Travel, because of my positive first experience. However, the bus was about an hour and a half late arriving into D.C., making me an hour and a half or so late to New York. (At least the outbound rush hour traffic wasn't so bad, though).

In anticipation of my next trip to New York, I might even avoid the Chinatown bus quandry altogether. I am planning to take Vamoose! back from New York because it lets passengers off right near where I live. The website is nicer than those of the various Chinatown bus services as well, which gives me (a perhaps false) sense of faith in their timeliness and general safety. However, if I leave after work on Thursday, I will have to take the Chinatown bus, because it leaves not far from my office. My question is, do I stick with New Century Travel and risk delay (or risk a more unpleasant experience, as happened to one of my coworkers, who got stuck on a New Century bus that was overheated and had a broken toilet), or is there another more reliable Chinatown bus service?