CallApp is okay... I am an early adopter and have been a long-time user. I simply didn't like that TrueCaller required access to my Google account. CallApp also has ads, but at least they have the one-time purchase option, and they have dialler theming, which I don't like.
What I can say about CallApp is that the caller ID is super quick, which is why I have stayed with the product.
I also use it alongside Drupe, which mainly serves as my phone directory, but CallApp is the superior dialler.
For those who use Samsung Smart Call, which is powered by Hiya, you don't need these caller ID apps though Smart Call is a limited Hiya version, but it is more than doable to block 'unwanted' calls.
I would up vote CallApp.