Whats better 2x4gb or 1x8gb

[mate.stanojkovski]

So i am building pc and idk what to put 1x8 3000mhz or 2x4 on this motherboard MB Gigabyte Z370M-DS3H

 

[USAFRet]

MERGED QUESTION
Question from mate.stanojkovski : "Whats better 2x4gb or 1x8gb"

So i am building pc and idk what to put 1x8 3000mhz or 2x4 on this motherboard MB Gigabyte Z370M-DS3H