Openings

Opening are not the most important part of the game

But it help you get a win to be in position to actually get in checkmate

Which one helps u get to the winning spot?

Studying openings before your tactical skills are at least on an expert level is essentially just a waste of time. Sure, by memorising openings you can hang on in a game against a better opponent for a good 20 moves if you're lucky, but unless you know the principles behind the opening and the tactical ideas that spawn from it, you're just delaying the obvious. Grab a tactics book and until you're absolutly certain that you can't come up with an answer - don't peek at the solution. You'll increase your chess skills far more effectively by doing some thinking, than memorizing any number of openings.

The answer depends on the individuals particular weaknesses as a chess player. If for example, a player has a really solid endgame, but has a lousy opening/middlegame, then their skill in endgames becomes irrelevant. 

Conversely, if a player has deep opening knowledge, but has little or no endgame, then the opening knowledge is generally useless as the player will likely mishandle won positions as the game approaches its conclusion.