I have both too, it's funny I consider them the opposite way to yours, I like Favorite as a cross body (I add a key chain as extender) or wear its long strap as a long shoulder bag; Eva as a short shoulder bag wear its chain only because the drop is nice and comfortable.
I mostly wear my Favorite as a shoulder bag. I wear both Eva and Favorite as shoulder bags with the short chain sometimes. My main reason to like the Eva as a travel bag is the zipper and the crossbody strap. I have used the strap from the Eva a time or two on the Favorite to make it more comfortable as a crossbody, but mostly I just use the strap that came with it and wear it shoulder style. I love that LV is so customizable and everyone can do their own thing with various straps, chains, charms, etc.