Which is the best wallet for bitcoin with the tiniest fees?
There are different types of wallets. You can choose between online-, hardware-, lightweight-, mobile- and classic (full node) wallets.
The transaction fee is not dependend on the wallet you use. Its depending on how much transaction are waiting for confirmations.
You can check the current average fee to get your transaction confirmed within x blocks here:
https://bitcoinfees.21.co.
What you are basically looking for is a wallet with adjustable fees.
If you are looking for a wallet for your desktop pc i would recommend electrum as a lightweight wallet (does not need whole blockchain).
You can adjust fee as you wish within electrum.
If you want a mobile wallet i would recommend mycelium. The fee is "pretty adjustable". You cant set it manually, but you got a lot of options
to chose from. Those range from 10 B/Sat to 300+ B/Sat.
If you are going to store big amounts of bitcoins you should use a paper wallet or (for better usability) a hardware wallet.
A more detailed list of bitcoin wallets can be found here:
https://www.weusecoins.com/en/find-the-best-bitcoin-wallet/