Responses take time, especially a good one. You can't expect a fast response.

Honestly, it depends on what you have. No point on getting a ninja that might not work with what you have. If you get Kushina and you plan on pairing it with Killer bee, who's the last ninja and what main are you thinking of using. If you get minato, who are your two ninjas going to be? Since I don't know what you have, for the safe choice, choose Kushina with kurenai (you must have her skillbooks) and be water main. With minato, you need a lot of work done with getting his bond skills, and I can't see how long you are wiling to wait to get other event ninjas that can pair him nicely.