There are very few specialties you can do at the same time. Even people that do combined residencies usually end up doing one specialty and forgetting the other.
If you truly like clinic and undifferentiated patients, but want the ability to perform cesarean sections and see “high risk OB” then family medicine with an obstetrics fellowship is ideal.
If you want to do gynecological surgery in addition to obstetrics, while being able to perform primary care for young, uncomplicated females, then OB/GYN would be ideal. The caveat is that gynecological surgery might become its own fellowship in the near future. Hyper-specialization despite midlevels “being able to do our job” and all that.
I’m biased towards family medicine, mostly because differentiated patients tend to be boring. Most of the thinking is done for you. But it is frustrating that 20-30% of your patients will end up needing a cesarean section through no fault of your own.