Definitely go for the name you actually care more about. EmmelineBelleElizabeth is really lovely and the flow is fine.There are many other names with the same cadence as Marie though - maybe keep looking? I mean, if the rhythm is important to you.
Belle & Marie are both honouring names, as well as Elizabeth. They're set in stone. I don't think i the cadence means more than the name I love, especially since I like EmmelineBelle.