everybody has asked this question, argued about it, and gotten mad about it. but what takes more individual player skill. high end arena, or end game raid progression. this means knowing your class, knowing your enemys/groups class, knowing when to do all your stuff. ( cd, rotation, gtfo-ing fire, etc...). and basic knowledge of the game. you can get carried in both, to a certian extent (imo).
and also, whybdo you think your choice was harder?
imo pvp is harder. you need to know your class better, know how to survive on your class, need to know the right time to use cds, and its way harder than standing around with a 3 button, rinse and repeat rotation.