Owen- This one fits with Ava very well, especially in that they are both very, very popular. Ava and Owen is cute.
Carter- Not really a fan.
Liam- Never liked this name. It's a nickname for William, so it seems incomplete on its own. If your last name starts with an M, don't use this one.
Easton- On its own, I like this name the best. It's the most unique of the choices, and I can see it both on a child and an adult. Plus, East would be a cute nn.
#1 Easton #2 Owen