I heard that hardware wallets are the way to prevent that... but what would be the best one?
Best depends on your needs (usability, safety, number of different altcoins you want it for along with bitcoin). It's hard to tell which is "best".
I heard that Trezor or Ledger hardware wallets are pretty good... but what do you guys think?
Yes, they're are the most used ones because they have an older history and reasonable prices.
However, Trezor doesn't have secure element chip and Ledger has a recent history of fuckups, from getting customer info (incl. addresses) stolen to faulty parts.
Plus, the communication with the companion software wallet is done via cable (arguably no longer air gapped) or Bluetooth (arguably not that secure).
If this is a problem for you, you may also read about
SeedSigner, which uses images for communicating with the software wallet, but keep in mind that this is basically a Raspberry Pi with custom software, hence no secure element and the name is not Hardware Wallet, instead it's an air gapped signing device. Bitcoin only.