The X-01 power armor is a set of power armor created by the remnants of the U.S. military after the Great War. It improves upon the pre-war suits by offering superior protective abilities. The power armor bears considerable resemblance to the advanced power armor seen in previous Fallout games, mainly due to the helmet design and general style. X-01 power armor provides the greatest defense among all other models of power armor featured in Fallout 4 thus far.
Fallout: Beginning Vs. End (i only have Fallout 3 and New Vegas, i don't have Fallout 4 yet, but I've heard talk that you get pretty decent armor and weapons right at the beginning... Anyone wish to clarify this?)