Well it depends how much CPs do you have. If you are F2P or not.

But in my opinion Edo minato is much better choice then Kushina in the long run. DOnt get me wrong Kushina is still amazing ninja but with Minato you can make a lot of lineups. Later on when you get his barrier you can even run him as a support on pos 3/4.

Cant really say what are the best teams but there are few easy one that dont require you to spend ingots. Kushina-Gaara Kazekage-Bee -earth or fire main. Or Kushina-Hashirama full BT- Shikamaru chunin BT- Fire main. And my favorite Kushina-Gaara Kazekage-Iruka-Earth main.

Minato can be used with ninjas like Gaara kazekage if you dont have minato barrier. And you c*e Iruka or Bee as a 4th ninja. Earth main works great with him.

And i woldnt use Kushina and Minato in the same team unless you have minato barrier and you run him on pos 4. There are a lot of teams out there who are using 3 strong pos 1 ninjas in the same team and then they lose hard because they dont have any buffs or support.