What is your favourite calculator?

I'm trying to find a calculator as good as my old Texas Instrument TI-89. I liked it so much that I continued to use it for many years on my smartphone with an emulator from F-Droid, also by laziness to find something better and more modern.

But I recently switched from Android to iOS and you can't find a TI-89 emulator on iOS. You have a few web based online but they are not very nice to use.

I got the WolframAlpha app as it is often recommended, but it is super slow and cloud based. And you need to reformulate some queries a lot before it does what you want. However, the Apple app store is full of calculators that all look relatively nice. I havn't found yet one as powerful as the old TI 89 or the Voyage 200, but I guess it does exist.

The closest modern match I found so far is the Numworks emulator app, but it's not as nice.

So what's your favourite calculator ? You may prefer GNU bc in a shell, or a mechanical calculator.

https://cloudflare.f-droid.org/en/packages/com.Bisha.TI89EmuDonation/ https://www.wolframalpha.com https://www.numworks.com