I would suggest trying to narrow down your choices based on your strengths and weaknesses (and those of your co-founders if applicable) and which ones you believe in the most; which would you buy/use/subscribe to as a consumer? This should give you a short-list where you could then perform a SWOT analysis^^ on each to help you trim the short-list of ideas down further. Get it down to one idea you are passionate about! Bring that to HN for feedback and you'll definitely have a great start!
^^ You mentioned you have done countless hours of research for an idea... Sometimes 'searching' isn't enough. Put your energy into 'doing' instead. If you're technical, create a prototype and unleash it to some people in the industry you are targeting. If you aren't technical, go find your pilot customers you want to target this to and present them with some wireframes and your elevator pitch for the product. Both of these methods will ensure you only spend a few days max but you'll be able to receive invaluable feedback to determine if you need to adjust your idea or try another one completely.