It depends on your risk-aversion. But I would probably say that 3.2.x is the safest route. It has the latest servlet containers, the datasource configuration is simpler than 3.0.x. It has more rigid deployment configuration checks. It will probably have a bigger base of free support here through the next quarter. Read the FAQ on 3.2.0 changes to get a feel for migration and features.
4.x incorporates AOP and the associated supporting architecture. If all you are doing in the medium term is EJB/servlet work, you may not want the additional features of AOP and the additional resource consumption.
3.2.x gives you leading edge, without giving you anything over what you need for the medium term. If 3.2.x had come out sooner, we wouldn't have bothered with the porting work to 3.0.x from 2.4.x.