Qigong is not for self-defense but it can help with it and there are 3 categories of Qi-gong; medical, scholar and martial. However the marital is more supportive to the self-defense side than actually used for self-defense. However with that said I have been told and read that both Baduanjin (8 pieces of brocade) and wǔ xÃng (5 animal frolics) had martial applications at one time.
Internal CMA styles
Xingyiquan was trained to the Chinese military at one time so yes it is good for self-defense and rather aggressive too. But you will see a difference in the traditional version and the military version as it applies to training
Baguazhang also good for self-defense but takes longer than Xingyiquan to get there
Taijiquan good for self-defense but it takes lo9nger than Baguazhang to get there and it is really hard to find a teacher that knows or trains the SD
Not considered internal but it does have its internal bits
Wing Chun; good for Self-defense and after about a year of good training you can use it
Praying Mantis is considered an external style and I know little about it other than a Southern Praying Mantis guy beat the heck out of me many years ago. However Southern Praying Mantis and Northern Praying Mantis are different.
Now the categories of Internal and External mean little and you really should not focus on them. There is an old saying that says "Internal goes to External and External goes to internal" basically if trained right they all end up in the same place