Is it based on ease of development, potential revenue, how interesting it is, ease of marketing the idea, time to complete...what criteria do you typically use?
I must add that, after 2-3 weeks, most of these exciting ideas sound really bad to me. There will be a few that will still sound exciting. These might be ones that are worth pursuing.
Pick the idea(s) that:
- is the simplest to launch right away,
- has existing demand (being searched so you get a sense of the level of ongoing demand),
- has lower competition for keywords (you want a killer blog anyways so you don't pay for ads as much),
- you can start optimizing for organic SEO today, via a BLOG talking about the problem you're solving WHILE you write the project. Rank early for the terms people are searching for or the problem they're talking about.
- is financially viable (calculate your conversion rate from traffic and if it would pay for itself if you used adwords vs organic). The lowest plan should pay for itself plus 30% minimum if not 50.
- leans towards small business tools, because 10-20 customers at $50 get you going much quicker.. ($50/month for a business is also like a $5/month expense for a consumer SaaS product -- we don't think about it at that level).
- appeals to business decision making .. businesses make logical decisions a lot more than consumers, who like making irrational, how it makes me feel decisions. Being a developer I'm much more able to pitch the logical value/benefits than dealing with irrational consumers.
0.02 :)