The reunion between the Stark sisters, Arya and Sansa, was emotional for sure, but not without awkwardness, particularly when Arya casually mentioned the list of people she plans to murder. But who is left on Arya's kill list on Game of Thrones? She told Sansa that most are already dead, but she's still got plenty of vengeance left on that list, particularly if she plans to do in Queen Cersei.
Some people on Arya's list were killed by others for her, like Joffrey, who both Sansa and Arya say they wish they'd killed themselves. Sansa is probably less earnestly wistful about this than Arya, who always kept him at the very top of her list. Others Arya killed herself, usually in a spectacular fashion, like when she attacked Ser Meryn at the brothel in Braavos by posing as an underage prostitute and then slitting his throat, or when she fed Walder Frey pies baked with his sons and then slit his throat, or when she murdered an entire room of Freys with poisoned wine. Arya still has several names left, however, and as the plot starts picking up and things happen more quickly, I have a feeling that these people are not long for this world.
The evil queen is still at the very top of Arya's list, primarily for setting up Ned Stark, organizing the Red Wedding, and slaughtering half of her family. Fair.
Ser Ilyn Payne
Ser Ilyn was the executioner who cut off Ned's head on Joffrey's command. He hasn't shown up since Season 2 so you might have forgotten him but Arya certainly has not.
The Red Woman took Gendry, whom Arya assumes is dead, for his king's blood. If Arya ever encounters her again, the night will certainly be dark and full of terrors indeed.
Beric Dondarrion & Thoros of Myr
They sold Gendry to Melisandre and they let The Hound go free. I hope Arya remembers to kill Thoros first so he doesn't bring Beric back to life.
Yes, he did kill the butcher's boy on Joffrey's orders and he's known to be a less than delightful character, but he did shepherd Arya around the countryside for a while until she left him for dead. Maybe she'll grant The Hound a pass?
He may be kinda, sorta, dead already strictly speaking, but I doubt very much that that matters to Arya. She'd still try to take him down for good.
There are others who have wronged the Stark family that didn't make it on the list (Theon Greyjoy and Littlefinger both come to mind), but Arya seems to have a full enough plate as it is. Because she's at the top of the list, could Arya be the one to kill Cersei? Personally, I kind of hope so.