The Frequently Suggested Topic is a great place to start but as mentioned here by ssilk many suggestions are on the Devs radar, you just don't know.
My suggestion is a simple list of suggestions and where they rank for the devs.(2 topics that got me started on this one here and the ssilk reply mentioned earlier)
Some groups could be:
Will be implemented eventually
https://forums.factorio.com/forum/vie ... =14&t=6847
Needs new content to know how it will work
This would include things that are a good ideas but until the new circuits or the factions or whatever comes out or implemented they can't be fully discussed.
https://forums.factorio.com/forum/vie ... =14&t=8352
Highly suggested and on Devs radar (ie not dead and doesn't need resuggestion so Devs know we want it)
https://forums.factorio.com/forum/vie ... f=6&t=3904
https://forums.factorio.com/forum/vie ... f=6&t=5011
Frequently suggested but unlikely to be implimented
Things that have been thoroughly discussed and might not happen but that doesn't mean you can't try again
![Smile :)](./images/smilies/icon_e_smile.gif)
https://forums.factorio.com/forum/vie ... f=6&t=7475
These are just to name a few and I'm missing a lot of topics that I know about that can't be implemented yet or that won't, but that doesn't mean you shouldn't try as suggested on the Read this or be Ignored number -1.
Hopefully this will help.