It depends.Big worlds can be exciting if there is always something to do and it is not big spaces betwenn quests.And the same can be said for small worlds, since it is easier to make it more enjoyable, due to better design, more content per space and so on.I personally like both, something even liking more linear games than open world games, because they sometimes tell better stories or is more enjoyable overall, becuase they dont have the "feeling empty" problem

My (locked) thread about how difficulty should be a decision for the developers, not the gamers.