Dude if you're a first time user and have no previous experience with Linux, then in your case especially when you're building a new PC, it goes by the rule of thumb that you should use Linux as a secondary operating system and Windows as a main one and if you feel that you could work with it then remove windows if not then do it the other way.
It is reccomended that first time users not abandon Windows completely because the transition is not as easy for many.
But ignore this if you're a longtime user or are installing linux on a spare computer for trying.
Here are my best:-
Ubuntu:- My personal favorite, best one for a newbie and always will be my "gateway" distro
KodiUbuntu/XMCBubuntu :- Turns any spare PC you have into an almost complete media solution
PearOS :- Many use this because of its resemblance to Apple iOS, although its been discontinued.
ArchLinux:- Lets you select what you want from ground up, very stable. Not acquainted with building it? Many pre-built Arch based distros exist.
Puppy Arcade:- Turn your old PC into a wayback retro machine. Very lightweight as it is based on Puppy Linux.
Many many more http://distrowatch.com/
Almost everyday someone comes up with something, but in the end what you want matters and the best linux distro can only be decided by you.