The default nuggets "[[[" and "]]]" are a somewhat common combination when building a json structure that has arrays within arrays.
Since most people will not change the default, we should try to make sure we pick one that is failry unique among the domains we are targeting (C#, Razor, HTML, Json, Css, XML and all other web-related techs for .net based websites)

I've opened this issue so we can track suggestions as well

I've been experimenting with '[||[' and ']||]', and they seem to work pretty well as '||' is generally used as an or operator that is binary which will make it fail because of the brackets so it is very unlikely we'll run into a case where this has a valid meaning in one of the targeted domains.