When investing in industry/niche ETFs is it better to focus on ETFs with broad exposure or a more targeted one?

Let me clarify what i mean:

\* "broad exposure" - if a company has even tangential exposure to the niche, then it's included in the index. That is, even if that part of the business is small

\* "targeted exposure" - includes only (or mostly) companies where the primary business is the target industry/niche

From what i can tell, "broad exposure" ETFs seem to be larger (in niche industries) and so therefore better in the sense that it's not cheap to "roll your own ETF". The targeted ones seem to smaller and a) you really gotta do your homework and b) you may not agree with the picks

So IMO it might be better off going with the larger niche ETFs. But what do you think?