I have a few apps on the AppStore, Quotegram, Islamgram, PrayerTi.me, and I would love to build more as there is no end to great ideas for Apps. Given the broad International reach of the AppStore without any overheads of cross-currency issues and such it feels best to be on the AppStore. At the same time, there is not much money that I can make with these smaller apps unless some of those make it huge. I don't want to slap ads on these apps as that would ruin the user experience. On the other hand I've been toying around with a SaaS business idea that would possibly bring in monthly revenues but the market segment is not great at doing online activities but certainly there is a need. I'm confused on which of this segment to choose to spend my time and energy on. Any suggestions?
Certain concepts work a lot better as apps and don't make a lot of sense as web services. I would strongly encourage you to read how Trevor succeeded with his Spanish Bible app - as niche as you get:
And don't be afraid to charge money for your apps (either upfront or as an in-app purchase). Advertising doesn't work for every vertical.