I think you can get a decent job with either the A or B. It depends on what you want to do. The class A is the popular answer. But, getting in will be harder and the training will either cost more or you will have to commit yourself to a contract with a carrier like Schneider or Roehl.
Or...you can get a class B almost on your own for about $750 w/hazmat and do expediting. Companies like Landstar Express America, Panther II, and Express 1 do a lot of work with what they call "D" units. That is a 22' - 24' straight truck w/sleeper added. Check out
http://www.expeditersonline.com to get more info. What you would do is work for a fleet owner or buy your own truck and be an o/o. They deal with priority freight which is time sensitive. Sometimes you get freight that has other special handling requirements. You can make good money doing that. You have to crunch the numbers though. You dont typically get as many miles in expediting, but...from what they say you get more $'s per mile. The pay off is less work for = money, or close. Less time, effort, and money to get your CDL. Plus, its easier to drive a straight truck than it is an 18 wheeler.
But, it comes down to what will make you happy. IMO