So, which one to use? Or how to mix them?
This can be related to the amount of content you have to offer and the value you can provide to the player. The more value and more valuable content you have, the easier it will be to try to monetise.
If you have a small game with like "one mechanics innovation", bunch of levels and power-ups, no social features, no long-term goals and meta game, I'd go for the ads.
Banners are pretty outdated and provide very little income.
Rewarded video ads provide more than interstitials.
It's a question of where. Good places are when level is completed. Especially when player has been successful.
Have some logic to it. Don't flood the first levels too much with ads.
Provide an option to get rid of the ads.
Originally Tetris did not have ads. Now you could have banner ads in every page or show video ads now and then. For games like Tetris, the best place would probably be to show always right after one has completed a level successfully!