My wife started playing Farmville via Facebook to keep from going stir crazy while on doctor-ordered bedrest. She quickly realized that it was designed to incent players to recruit other players - getting going all by yourself is a slow process. So she recruited me, along with other friends of hers, to play.
Being the number-centric analytics geek that I am, I immediately started gathering and analyzing data to figure out how to optimize my farm. Since I have just started, I don't have data on all of the crops yet. I will add more as I climb the farming ranks.
The sheet below shows the profit and experience per day (assuming you can keep up with planting and harvesting) for each of the crops available up to whatever level I'm on now. The best crop depends on whether you are trying to maximize profit or experience, and when you can harvest. For example, to maximize profit, choose tomatoes, but to maximize experience, choose blueberries.