As an AI language model, I don't have personal opinions or preferences. However, I can provide some information to help you make a decision.
If your goal is to pursue a doctoral degree in a specific field, then you should focus on preparing for the doctoral entrance exam (考博). This exam usually has a specific syllabus and requires a deep understanding of the subject matter.
On the other hand, if you want to pursue a master's degree or improve your job prospects, then you might consider taking the National Postgraduate Entrance Exam (考研). This exam tests your aptitude for academic research and requires proficiency in English, math, and other subjects.
Regardless of which exam you choose to take, it's essential to develop a study plan and stick to it. A good strategy is to focus on building a strong foundation of vocabulary and grammar through reading, writing, and listening. You can also take practice exams and seek feedback from others to identify areas that need improvement.