So far, it's honestly Creed 2, but I haven't seen a lot of the like more Oscar-tier stuff.
I was really surprised by how good Creed 2 is though. It's very successful at being both a continuation and an extension of the narrative of the first film, and a movie that follows up the legacy of the Rocky franchise (in this case, the goofy ass Rocky IV). Rocky IV and Creed are both very tonally dissimilar movies but the way in which Creed 2 is a sequel to both of them is surprisingly successful. The movie also takes Adonis and Bianca and develops their characters and relationships in interesting and new directions that feels nuanced and human. The boxing scenes are not plentiful but when they do happen they pack a goddamn punch. This movie is missing Coogler's unique directing stylizations but I prefer basically everything else about it to the first. There was very little wrong I could find with it.
For posterity, here's my ranking of 2018 films I've seen thus far:
1. Creed 2
2. Three Identical Strangers
3. Deadpool 2
4. Won't You Be My Neighbor
5. A Simple Favor
6. Ocean's 8
7. Annihilation
8. BlacKKKlansman
9. Black Panther
10. First Man
11. Avengers: Infinity War
12. Mission Impossible: Fallout
13. Ant Man and the Wasp
14. Crazy Rich Asians
15. A Quiet Place
16. Love, Simon
17. Mary Poppins Returns
18. The Spy Who Dumped Me
19. Hereditary
20. Solo: A Star Wars Story
21. Venom
22. The Meg
23. Robin Hood
24. Uncle Drew
25. Skyscrapper
26. Life of the Party
27. Fantastic Beasts 2
28. The House With a Clock in its Walls
29. Jurassic World: Fallen Kingdom
30. Winchester
31. The Nun
A lot of what I saw this year felt pretty meh. 1-5 were pretty damn good, 6-12 were enjoyable romps, 13-18 were decent, 19-25 were mediocre, and 26-31 were all pretty bad. Not a 2018 movie but I also saw Perfect Blue in theaters this year which was easily better than everything else.