For a secure bitcoin wallet you shouln't choose an online wallet. You need a wallet which gives you (and only you) the control of your private keys.
Electrum is a trustworthy desktop wallet. It has a nice functionality and is IMO one of the best desktop wallets.
But you have to keep in mind that if your PC get compromised through malware, your private keys can also get compromised (depending on individual situations).
If you can afford a small amount i would recommend a hardware wallet. Those give you the best security because private keys never get exposed.
The signing of transactions is completely done on a dedicated device. But if you are only storing small amounts a desktop wallet should be appropiate.
But always use your common sense when downloading/executing any software on your pc on which you hold your money.