I am thinking about installing a wallet on my cellphone.
The main wallet is on other Devices and / or offline.
In the mobile wallet should be only a small amount for trying to buy something outside or for the ATM transaction or other transaction like exchange BTC with friends outside.

Which wallet do you recommend for a non-technical specialist in the above mentioned case?
Should be as safe as possible, only for small amounts, different coins if possible and fast update or updating in background with low battery use.

Thank you for your recommendations and answers.