For iOS, Tofu is simple and works very well.
i'm a big fan of hardware token - connected via usb/nfc!
especially because there is no need for a mobile device and they are fairly cheap.
and: because they are cheap, i'm using at least 2 per account/service where such keys are supported.
if i lose the one on my (physical) key-ring, i always have a working replacement at home ... :)
just my 0.02€
I assume you mean TOTP apps in particular. Anyway, KeePassXC and FreeOTP are both good for that.
I currently use the Salesforce one because when I upgrade my phone restoring the Authenticator on the new device actually works. If there is a better one I am all ears.
https://help.salesforce.com/s/articleView?id=sf.salesforce_a...