If you want the best and most up to date builds. Trust me on this, but item builds matter a lot. Its the core reason of why this game have comebacks and so forth.
Its best to look at the builds of the top players in the game.
Search up the summoner's name( get the ign from the first page of premade or solo queue), and see what builds they use.
If anyone have any questions, feel free to ask me. I generally remember the builds of the top players ( unless its a UP character like Eve x.x)