I used iAd a long time ago and it was pretty decent for revenue at the time. What are people using these days? What has the best balance of revenue and minimal user annoyance?

I’m planning to buy some adds and wonder what works the best. Apple search adds, meta adds, tiktok adds, google adds etc

I develop apps for the iPhone, iPad, Mac, and Apple Watch. What are the best (preferably free) to advertise/announce apps?

I am talking about posting promo codes, when this is the case, containing a description, link, image, etc.

I am aware of TouchArchade and MacRumors forums. These were great in the past, but currently such forums, at least in the section where you are allowed to post advertising/promo codes, have a very low number of visitors.

Please also mention paid advertising, and which are the best places or methods to do it (by impressions or by value per day?) and where (Instagram, Facebook, Twitter? ).

For the apps I've just released, which I want to promote right now, the target audience would be people who like science, space, astronomy, physics, and things like that.

What’s an example of the absolute very best and most useful app you use regularly that doesn’t contain advertising banners or pop ups?

Conditions:

Cost no more than $5/€5

Free is better

Used daily or several times per week.