Lets say i want to transact a very important huge amount of btc transation of my life. Which one should i chose between Offline signing transaction via Electrum(gpgverified) or trezor bought from official site.
Where are the private keys for this huge amount of coins stored at present? What about the seed phrase? Depending on how and where the seed phrase was generated might dictate which method you have to use, or which method is best to use.
Completely hypothetically, I would probably recommend a hardware wallet. I use both hardware wallets and cold storage, I feel my cold storage is probably marginally safer than a hardware wallet, but I also appreciate my cold storage set up is significantly more complicated than setting up and using a hardware wallet, with far more possibilities for fatal errors. If you are not sure which one is right for you, then the answer is a hardware wallet.
If you are super paranoid, you can always use your hardware wallet via a clean airgapped computer. This doesn't mitigate any physical attacks on the hardware wallet, but it would help to mitigate against things like clipboard malware or any unknown vulnerabilities which could leak your private keys from your hardware wallet.