You could back it up onto a few USB drives in an encrypted container perhaps as an alternative.
The problem with encrypted containers is that you can always forget or lose the encryption key(s).Piece of paper for me.
The safest of all things that have been created.
If you put it in the internet it is not safe. You input it in a USB still not safe even if encrypted one.
I just got two copies that have been written in a paper. One is in my storage of important things and one is being held by my wife which I dont know where she keep it.
+1 paper
I am of the opinion that SEED should never be on ANY computer ever, unless I need to do a recovery from total loss [I am not disrespecting the Electrum two computer cold wallet approach but even that falls short of hardware wallet security]. I use hardware wallets but they still use a SEED for recovery. A functioning hardware wallet never shows the SEED to any computer. The exact day that I ever place a single SEED on a computer I would immediately create a new wallet and move all coins to it. SEED is for recovery only. If I write my SEED on paper then it never sees a computer. If you can't secure a piece of paper with a few words on it, you need to possibly reconsider this hobby. Seriously, as BTC is now worth several thousand per coin, one mistake on this and you can lose it all. BTC hackers are freakin writing some awesome code and it takes a computer to hold code. My .02
edit: OP I re-read my post and I don't mean for the tone to sound "in your face". I do computer security and I don't care where you store your digital files (usb, hard drives, etc...) they can be approached by great malware. Malware can't get to seed that it can't see on paper!