Which market to target first?

My past posts have included discussions about the importance of a market niche and the importance of a product family (not a one-trick pony).  So, you've picked a niche and are developing a product family.  But how did you decide upon that niche?  Was it the largest one?  That would be a logical answer, but what if that niche requires much more money to develop and sell into?  What if that niche has a much longer sales cycle?  Be sure to consider all aspects of the niche you plan to target first.  The best one just might be the one that will provide the quickest revenue for you.  This is sometimes called the "low-hanging fruit."  Now that you have some revenue coming in from this niche, you can fund some other niches that might require more money to develop and/or have longer sales cycles.  Oh, and beware of niches that have seasonal sales cycles.