What are the best tools available to identify attractive industries/niches?

Hi all,

I'm beginning to prepare for my search and would appreciate your input on industry focus. What are the best tools and practices available for searchers to identify industries/sectors/niches with potential for a deep dive? I've explored a couple of options, but haven't found sufficient coverage of niche sectors.

My thinking is that there might be up-to-date databases that cover niche sectors for small businesses and could provide detailed breakdowns on key metrics such as ROA, number of employees, revenue CAGR, margins, number of companies, etc. If such databases aren't available, what are the best practices for building these databases from scratch?

Thanks in advance, Luis