Which had a better story, Gta V or Gta IV?

Different, but I would say GTAV

GTAIV was just the standard immigrant chasing the American Dream, except Niko relies on crime to do it.

GTAV on the other hand had a story that branched out between 3 characters. It all kind of revolved around Michael with Trevor representing the past he was running away from and Franklin as a new future. Through the game, the two parts of his life collide and then form into one. There is less of a passion maybe. Michael for instance starts the game pretty rich already, Trevor will always be a redneck, and Franklin experiencing the biggest "rags to riches" storyline. The GTAV storyline is more broad and their life styles seem to be more relatable.

The biggest difference in game play is that Niko is more of an assassin freelancer where as in GTAV, they are more a team of professional criminals.

There is also more weight on the personal decisions of the player in GTA5. In GTA4, the biggest decisions you had were if you wanted Nikos cousin or girlfriend to live. This happens at the end of the game and it really doesn't make much of a difference to gameplay. You will still get about the same amount of money from completing the missions.

In GTA5, your decisions on heist, how you spend your money throughout the game could mean the difference between millions of dollars. If you don't do it right, you can't buy everything you want and can't even unlock all the achievements since you won't be able to afford all the real estate. In this sense, the decisions you make in game will have a direct result on how your post story gameplay will be.

I like GTA V cause GTAIV was very boring and repetitive

To me is GTA4 because is more cooler and you don't have to spend money to buy cars all the time when required....