software process model for one person with requirments well defined upfront a project developed by just one person that have all the requirements well defined upfront which is the best process model for a cms project? Im in doubt between agile or waterfall. I read that waterfall is ok for projects where the requirements are well defined and is not probably that will change, and it is the case, but also i read that are a lot of disadvantages. But also agile it seems that its more for teams with 2 or more people so maybe its not appropriate. Do you know more clearly which criteria should we have in account to know which is the best process model?

If you have just a single person with all requirements clear, you don't need a process model at all. You grab the list of requirements and turn them into working solutions one after the other.

Please note that due to having been in at least one project, I don't believe that something like a "clear upfront requirement" exists. Who do you communicate with? Who is your customer? You need to find a way to communicate him the status and the current feature set, so this person can decide if the project should continue in the current direction or if more people are needed to keep the deadlines or maybe the requirements _did_ change (shocking!... not).

You don't need to decide on either waterfall or agile, but you need to find out who your customer is and how to make him or her happy.