Can someone tell me what is the currently the ledger wallet that is most secure? If not Ledger then what is the best cold storage wallet in your opinion & what facts do you have to back that up?
I'd personally recommend something not Ledger-branded; if you want a tried-and-tested brand, get a Trezor product, otherwise I'm a big fan of the convenience and open-source nature of the
Foundation Devices hardware
wallets.
In terms of supply-chain attacks (the scenario described / worry about it described here); some brands rely on stickers, others give you more options.
Passport has a 'supply chain validation' process where cryptographic signatures are used to make sure the device is genuine; the device also verifies signatures of any updates you install to it (just reinstall latest firmware when you get it) and you could even easily build the firmware yourself and flash it, after uploading your own keys to it.
Open-source hardware also allows you to visually inspect PCB and internals for any
hardware implants or similar supply-chain attacks on the hardware level. Although I must admit that they're not the easiest thing to open (without damage).