1: What features you want to see in a wallet which is not in other ones
Does open source count as feature? I wouldn't call closed source wallet (trust wallet and exodus) a good wallet. Ability to have access to seed/private key and able to import it to another wallet is important for many users.
I tend to agree with this, the open-source wallets feature are the best wallet for me.
IMO, the best feature that wallet has that free to download is Electrum, it's a decentralized and fully open-source wallet. The most popular and wallet and it has a cool range of features, especially the adoption of Lightning Network the recently launched.
The most important is the encrypted private key, you should have full control to keep it safe. You have the ability to export your private key so that you can able to access your wallet on other Bitcoin clients.
Fort further information, look at this
Electrum Key Features.