we had this with dd2 (dd1 we just seemed to agree on - eventually!)
we had what we thought were her two middle names, but despite making lists and lists of names we couldn't agree on her actual name.
We both had names we really loved, but which the other thought were just "ok".
This went on right up until she was born, and she was nameless for a week or so.
Then we hit on the idea of using one of her middle names as her first name, as finding another middle name wouldn't be too hard, since there were many we liked well enough, but couldn't imagine using day to day.
This worked for us, but may not be much help for you if you are stuck on middle names too!
We had to use the name we did (having decided to go with one of her middle names), as out of the two, dh really didn't want to use one of them as a first name, so it was decison made, really.
We now call her a totally unrelated nickname anyway, but we do that ith dd1 as well!