Before deciding on which certification to choose, ask following questions to yourself:
- What is the end goal? Are you interested in getting into Project management or know more about iterative model of development
- Do you want to have broader learning graph? Agile is definitely subset of PMI framework
- If you have temptation of moving out of software industry in long run, agile is definitely you should avoid.
Also one thing we need to understand is Good PM is not born from Certifications, it is the experience and willingness to learn...