DC is the basic form of "Electricity" since it was discovered and the raw material generated into any generator windings now ... ( Escaping some details here to keep it simple ) it is converted instantly to AC ...
which we use daily/safely in all home appliances.
Safety is very important for both DC/AC techniques as they both can cause fire and many other hazardous dangers ... And when some one clearly "Newbie" asks what should I use for motor ? ... the expected answer will take in consideration your DIY ability and the simplest choices of all related next motion control boards and their prices and how many members can provide you with a wide variety of good support on the mechanical and electrical side of the equation ...
That what makes DC is preferred to be used for Newbies and any low budget simple typical project.
We all used DC "Me

Credit @speedy: http://www.xsimulator.net/community/threads/newbie-advice.6738/page-2#post-75562