I would say you are putting the cart before the horse. You need to decide what you want to do, and then get the best tool for the job. It also depends on how much experience you have. If you are just starting to learn about micro-processors, the Galileo may not be the best choice.
You also need to consider what programming environment you want to work in.
If all you want to do is run Arduino code, get an Arduino Uno. The Arduino Uno is a great board to learn with. There are a lot of examples, the environment is mature and, unlike the Galileo, it is hard to destroy it. (If you do burn out the pins, and you got the version with a removable chip, you can save a lot of money and just replace the chip).
if you need precise control and/or have a simple project, then you should still probably get an Arduino Uno. After you learn a bit then you will be able to do a lot more with the Galileo.
If you want to have learn Linux and want to have a project that connects to a display, you probably should go with a Raspberry Pi. There are a lot of examples and a great community, but it doesn't use Arduino shields, so if you want to have a real world interface, finding quality daughter boards and other parts that fit your needs may be a problem.
If you want to use Linux, need precise control and won't use much memory, than an Arduino Yun is a good choice, although the bridge is a bit complicated to use and there aren't a huge number of examples of projects.
If you want to make something that needs a bit more memory than the Yun, is simpler to code (no bridge), doesn't need precise control, and want to take advantage of the enormous number of shields and add-ons that are made for Arduinos, you should use the Galileo. If you want to learn to use Node.js than the Galileo with XDK IoT is a good choice. If you want to use Python and Arduino shields you can use AlexT's version with wiring _x86. Just be careful as it is easily damaged.