The obvious question is how much money do you want to spend?
From a price/performance point of view the desktop will cost less and also provide you with higher performance assuming you spend the same amount of money on a desktop or laptop.
From an upgrade point of view, the desktop is both more easily upgradeable and also costs less to upgrade compared to a laptop. Most laptops limits you to just upgrading the RAM and hard drive. Some also allows you to upgrade the CPU as long as it is not soldered into the motherboard. However, when it comes to upgrading the graphics, this is very rare. Only certain expensive gaming laptops allow you to do so. Therefore, you must do your research if you want to be able to upgrade the GPU in the future. Finding a laptop GPU is another problem and they are expensive to very expensive.
The one good thing about a laptop is that you can carry it around with you.