Both is an about euqally difficult problem, but modes that require a nonce fail much more spectacularly than modes that require an IV. Typically with a re-used

Both is an about euqally difficult problem, but modes that require a nonce fail much more spectacularly than modes that require an IV. Typically with a re-used IV the same plain text will lead to the same cipher text, which can be an issue. On the other hand with a re-used nonce you can basically recover the xor of two plain texts from two cipher texts. This leads to plain text very quickly and is a much more serious issue.