Which motherboard should i get?

I know the basic stuff about motherboards, but im building it myself and it's my 1st time so is there any difference in motherboards for building on it, i have done my research but i would like it to go as smooth as possible.
 


2400 mHz ram is cheaper than 2133mHz for about 10 euros, and it says it supports 2400 (O.C) mHz and for example z170a tomahawk don't have O.C behind the 2400mHz so, is there any difference in it?
 


Thanks a lot for the help, also i'm thinking about getting Enermax Maxpro 500w or 600w PSU, is the company and the series good or should i look for something else?

 


Ye i was looking into the SeaSonic S12II series 620W 85+ PSU, since it has a good price, and what i have learned, SeaSonic makes great PSUs.