Romanization of じ and ジ with ji and zi


From some basic research I've found that when romanizing じ and ジ we can use
"ji" or "zi." Apparently "ji" is used by Hepburn romanization which is the
most popular for non-Japanese speakers but "zi" is used by Nihon-shiki and
Kunrei-shiki romanization. I read Kunrei-shiki is what is taught to Japanese
elementary school students (and it is what my 20 year old Japanese textbook
used).

Also, when doing a google.co.jp search for words romanized with "zi," google
will sometimes actually ask if you meant to search on the Japanese version of
the romanized word, so it recognizes it as Japanese.... but it doesn't
recognize words when using ji.

So I figured "zi" was more common and better for Japanese people... but a
Japanese person I know just old me "we never use zi and always use ji." So,
what is the deal here... is one better than the other (and by that I mean is
one going to be easier to understand or more natural for native Japanese
speakers)?

As an aside that may provide context for an answer: the reason I'm asking is
I'm trying to choose a social media handle with Japanese in it and am trying
to decide on zi or ji...




With regard to zi or ji, ji is the right choise.

With regard to Hepburn or Kunrei, on the other hand, it is difficult to
answer. Schools teach us in Kunrei-shiki. However, when we apply for a
passport, we must write our names in Hepburn. According to
[wiki](https://ja.wikipedia.org/wiki/%E3%83%AD%E3%83%BC%E3%83%9E%E5%AD%97#.E8.A8.93.E4.BB.A4.E5.BC.8F.E3.81.AE.E8.A1.A8),
Kunrei-shiki is still the official one, but even the government officials use
both styles.

