Litecoin Core is the reference client. This means that any and all tech running on the Litecoin Network is built upon Litecoin Core - and thus it is pretty secure.
However, if you are a new users I would suggest using a lightweight wallets such as Electrum-LTC or Exodus.io. If you're on mobile, a popular lightweight wallet is: LoafWallet. These clients don't need to sync for hours, and you can retrieve all of your coins from a twelve word recovery phrase.
Lightweight wallets are just as secure as Litecoin Core, if not better. For example: to steal coins from LoafWallet iOS you would have to break iOS security. The exploits needed to do this would likely cost hundreds of millions if you sold it to a Government. I don't think it's worth the crime for the potentially slightly large amounts of LTC store on LoafWallet.