It's time to list your topics in order of importance and preference based on the research you’ve done so far.
This won’t be final by all means, but at least if you put it in order now the next stages of niche research will be easier.
Don’t drop any of the topics yet. Until you’ve completed all the stages of niche research, you won’t know for sure which are the ones to go with – now or in the future. You also need to know what you considered this time around – even if you don’t go ahead and use it.
You can rank your topics however you like but some things you may like to consider when putting them in order:
Use a spreadsheet and rank your potential topics in descending order (best to worst), as it seems to you now without any further analysis.
You can come back and re-order the list easily when you get results from keyword analysis, competitor analysis and monetization.