Do you need to find out which crop makes you the most money? Perhaps you would like to maximize your experience? It isn't always easy to tell which one is the best to go with, so using this Farmville spreadsheet is your best bet. Right now, there is a nice drop-down style menu which can be used to show the crops that are available to you at your current level, which will help you decide which ones are best.
This Farmville spreadsheet is a work in progress, so keep coming back to check in to see if there are new things added.