The Simpsons Tapped Out. It's a town building game where you get to design and build your own Springfield. It's freemium, but I barely spend a dime for donuts (the premium currency lol) to bye more. You just have to save up them, and luckily with the features you can have enough. I've been playing since 2013 and my town is huge. No ads anywhere.
There's Pokemon Go that doesn't have any ads, but I can't stand that game. It's a microtransaction cesspool these days, and the purity of it got stripped away long ago.