After sports science and blood bags it depends on what you want to do in torn. I jumped around and did everything that helped in combat and stats. But if you want to make flushie sets the museum makes sense, if you want to own a business then the business classes makes sense.
Also grabbing the classes that help crimes makes sense too. Things like cracking rig over clocking or the online store and passive scrapers and phishers for scamming. Most everyone agrees that sports science all and unlocking blood bags is a solid first choice. After that play style can matter.