depends on if you want to stay trendy, which Sawyer & Izabella are, even though you switched it up with the spelling and Holden seems to be one more and more people are eyeing
August - feels feminine, if you can use Augustus, love Gus as nickname, leads me to Gustave
Finn - TRENDY
Graham - strong, masculine, great pick
Jasper - TRENDY
Leo - common, try it as a nickname and use Leonardo, Leopold etc instead
Miles - TRENDY
Milo - TRENDY
Quentin - reminds everyone of the Director
You have a list of fine names, all of them masculine and wearable and any of them would be great with your other kids' names. My personal favorite is Quentin. It's such a cool name! I have no idea what "the Director" thing is pp is talking about. The only one I maybe wouldn't use is Finn, since you have a Sawyer already, unless you don't mind a little it of a, "Tom Sawyer and Huckleberry Finn" kind of theme.
Since you don't seem to be in love with any of these though, I'll try to think of some others might like. If you post back which ones you like (if any) we can help think of more ideas if you want them.