Personally, I can only recommend software which is open source, and this usually applies to almost all walks of life, but particularly encouraged if you are using it for finance related things such as handling money. Bluewallet as suggested by others is probably the most popular choice. Remember, whatever software you are using, you want to be able to trust it with the information you're giving it. If that's a private key you want to be sure that its secure, hence the suggestion of a open source wallet since it can be verified by not only you, but others.
I use Ownr wallet app on my iPhone. This wallet is relatively young and not so popular, but it offers such features as importing an old wallet and generating many Bitcoin accounts.
Also, doesn't really offer anything better than open source alternatives, not that I would wholeheartedly recommend people to use IOS wallets for anything other than a watch only wallet.