Are All Crops Created Equal ?
When it comes to selling crops in the market, the profit potential of crops is not the same across the board.
First you want to think about how active you will be in the game. If you are on a lot you can pick a much more profitable crop that requires more planting and harvesting time. If you only check in once a day or a few times a day, you want to pick a crop that is more slow-growing.
Here is a table of the profit potential PER MINUTE of time it takes to grow a crop, sorted from most to least profitable. In considering this table though, also take into account the principle of supply and demand. If you scan the paper, you will always see a glut or surplus of wheat being offered for sale. This means it is not that easy to sell at full price, because there is so much of it available. So even though it has the highest profit per minute of growth ratio, it is not a great crop to grow for profit because it can sit in your store for a long time unsold, unless you sell it for a low price (see wheating).
Experiment to find the best blend of desirability (how rare something is in the paper) with how much time you will be on the game and available to grow and harvest your crops.
(By the way, I have excluded bush and tree crops from this table, since they have the added cost of requiring an axe or saw as a cost of doing business. So if you are farming for profit, they are not always a great choice).