If not using official Apple charging cables I only trust Anker as an alternative brand. There's probably more that work fine but Anker is a brand that I've used extensively and can say with confidence that I've never had an issue with an Anker cable.

Anything with the MFi logo. Other than that, down to the length/colour/other end that you need.

I quite like Anker ones, used to get them off Amazon when I was living in the UK. You can get em off AliExpress.

lxsw20:

 

I quite like Anker ones, used to get them off Amazon when I was living in the UK. You can get em off AliExpress.

 

Mighty Ape also sell them.