A lot depends on what kind of data you have. In particular, thematic analysis can be applied to most types of qualitative data, but narrative analysis usually requires relatively rich accounts.

Thematic synthesis is much more flexible. If you're not sure whether to use narrative or thematic synthesis, thematic is probably the better choice. This is especially true as you're using secondary data --- there's a good chance that the data you have won't be rich enough for narrative.

I strongly recommend that you read Saldana's Coding Manual for Qualitative Researchers --- the book explains many approaches to thematic synthesis.

https://uk.sagepub.com/en-gb/eur/the-coding-manual-for-qualitative-researchers/book243616

Thomas' general inductive approach is quite straightforward: https://journals.sagepub.com/doi/abs/10.1177/1098214005283748?journalCode=ajec

The narrative analysis is good provided you are required to collect the case and primary data.

In any case, I think that the choice depends on your results synthesis.