Given your goals and interests, I would focus on building a focused solution for a problem you see in and around the work that you've done in the past.
Focusing on a problem space you understand and you yourself might be a potential customer for gives you a lot of advantages. If your solution can accomplish two big goals 1) make developers happy and 2) increase efficiency (reduce bugs, make releasing functionality faster, etc) then you'll have something worthwhile on your hands.
From a pure operational perspective, building a single focused tool that is low cost enough for a solo developer to gladly pay for or for an employee to gain easy sign off on will make support and sales much easier. By focusing on a simple solution, you also limit the breadth of the functionality you have to maintain. This will allow you to focus on refining and improving the value proposition and help minimize spaghetti code. It also makes growth possible with a small team.
A good example of this might be jell.com which helps teams handle standup and work visibility. Making a SaaS product with a low initial cost means you accumulate revenue over time. Compared with traditional software/app sales, you have a much easier path to sustainable monetization.
Good luck on the effort. I also recommend reading into the lean startup methodology and taking small iterative steps and measuring their impact to get started.
There will always be developers better than me but I am definitely better than "that guy" over there - and I am getting better every day.
I was concerned that I wasn't good enough and I almost treated the above statement as a mantra.