If you go by the films released between January 1st to May 3rd, 2018 then you'll see there were definite breakouts that merit your full-attention [IndieWire tried to reaffirm that point here].
A Quiet Place (John Krasinski)
Tully (Jason Reitman)
You Were Never Really Here (Lynne Ramsay)
Paddington 2 (Paul King)
Isle of Dogs (Wes Anderson)
Game Night (John Francis Daley, Jonathan Goldstein)
The Death of Stalin (Armando Vianucci)
I'll be going to Cannes next week, so I'm sure the below list will change. These are the upcoming summer releases, almost all above-average to great, which I've already seen at various film festivals:
The Tale (Jennifer Fox)
Custody (Xavier Legrand)
The Wife (Bjorn Runge)
Search (Aneesh Chaganty)
Actual 2018 top ten
3) The Wife (Bjorn Runge)
4) The Rider (Chloe Zhao)
5) A Quiet Place (John Krasinski)
5) Hereditary (Ari Aster)
6) Leave No Trace (Debra Granik)
7) Three Identical Strangers (Tim Wardle)
10) Sorry To Bother You (Boots Riley)
Criterion's December lineup has some great additions to the library, but the title that jumped out at me is Werner Herzog's "Grizzly Man," which officially joins the Collection on December 8.