The choice of choosing the tool depends on the kind of request you are going to get from the client or end user. If you can expect around 50 to 60 reports in 6 months time and the end user wanted to design many of them, then Choice goes to Cognos only if they can afford setting up a team of consisting of a Modeller and developers. The role of Modeller is to design the Metadata in Cognos that will be understandable for the enduser. The Modeller will be a person who has years of expertise in the business and should be knowing how to model the underlying data structure. The model gives enduser the business view. The role of the developer will be to develop complex Cognos reports that cannot be handle by the end user. Here the investment is high in Cognos. This is a long term process. Please keep in mind that not all Models are perfect. Not all request need'nt be possible to handle by a Model. It's always an evolving process.

But, If you are looking for very customised reports it's better to go for Crystal Reports. I believe the Cost of Maintenance is less here. Development complexity is far less compared to Cognos.