I'd say, out of personal preferrence, Sword and Shield.
Greatsword is nice for in general better damage and the ability to use the best possible damage skills, but the Shield block is also huge to miss out on, especially in PvP where a block can save a life.
I`d have to try Greatswords in different situations, but I could assume that Greatswords might be great for PvE, but for PvP I'd go for Sword and Shield any time due to survivability.