I'd echo cat's and others' views. Core systems such as combat should be completed independent of feature updates. While its nice to have new content and for example new animals and mobs, it doesn't make sense from a design perspective if combat hasn't been fleshed out. Without the core system implenmented it limits how these creatures can attack/interact with the player.
So I would say my vote goes to combat, so that more interesting content can be built ontop of that system. It may be boring, but its needed.