Delivering mate. There is nothing nicer.

The queen is the strongest attacking piece. So it delivers mate particularly often. Its mating motifs are the most important.
As soon as a file towards the opposing king is opened the rook becomes a killer. But be careful. It can also attack from the side: yoiu need to be able to spot a back rank mate in your sleep.
A king which is hemmed in and an open diagonal. Now the bishop comes into its own.
If the knight wishes to deliver mate it needs the help of its teammates. With the exception of a wonderfully beautiful example: in a smothered mate it defies all the defending pieces and finishes off a king walled in by other pieces.
Actually pawns are there to rip open the opposing king position. They are often sacrificed for that reason. But any piece which can give check can also deliver mate. With a little support from other pieces we can get some pretty mating patterns.

Mate wins the game. If you know the typical mating patterns that gives you an advantage. Even against good players they keep on occurring in blitz games.