How was Trezor (bitcointrezor.com) not mentioned here thousand times already? It's a 100% solution, an offline, standalone signing device. It's open source and it's securing bitcoins by the design of the process alone and not by a smartcard component like ledger wallet.
1) Expensive.
2) Not offline(aka cold storage).
Ledger is secure like Trezor. Don't think Trezor > Ledger!
Exactly. Nevertheless, you can find very informative posts (and links) here on how to create your secure cold wallet. Don't forget to store it in (at least) 3 mediums and in 3 different places. This will give you about 98% probability your funds are secure.