for the short term I keep it in myetherwallet, I also often keep it in the exchange, but not for long or just for the needs of trading. if to keep in the long term then I like and choose the hardware wallet to keep all the assets I have.
The Trezor wallet is one of the oldest hardware wallets in the cryptosphere and it is no surprise that it supports all ERC20 tokens. Just like Ledger, Trezor too comes with an OLED screen, seed key feature, PIN code protection and passphrase features to secure your ERC20 tokens. Also, Trezors development team is very active and respected in the community.
For me MyEtherWallet is my wallet storage of my tokens and it is a web-based open-source wallet written in Javascript. It is a user-friendly application for securing Ether, ERC20 tokens and interacting with smart contracts.
It claims to be an offline wallet as it uses a machines browser to generate necessary data, and nothing is ever stored on MyEtherWallet servers. Also, you get the private key control so you need not trust any third party for the security of your funds.