Coinomi would be such a fantastic wallet if only its code were open-source. I've never had any problems with them, but I can't say it doesn't make me just a little bit nervous knowing that the code hasn't been reviewed by any independent parties. I guess I could say the same thing about Ledger, too.
One thing about Ledger nano is that its secure element which it is using to generate and store seed phrase is close source, it is operated with an extension like the ledger live or wallet like electrum, some people still believe it can be trusted because of that, unlike wallets that spyware or other vulnerabilities can be introduced. But, also still very possible the secure element can have vulnerability in which predetermined seed phrase can be generated, that is why open source hardware wallet like Trezor is still better, but with the use of passphrase in case of physical theft.