Both are pleasent sounding, but
Lauren doesn't have the same "feel" as
Julia does, whch is a beautiful, well known name with a lot of great history.
Both are popular, but I think
Julia is less likely to date your daughter, as it's always been around while
Lauren became popular more recently. I know way more little
Lauren's than
Julia's.
Congrats, here's rooting for a little
Julia :)