Sebastian or James maybe?
Can I be very rude and this is only my opinion
I'm sure little Aubrey will grow up to love his name. But I would pick something quite run of the mill as you seemto be suggesting for his middle name incase he wants to use that in future
That saves the "Gideon" Osborne issue where he had to pick a totally brand new name George as he didn't want to be known as " Oliver Osborne" which was his middle name (presume it was the alliteration) so think how the middle name will go with your last name if its used aaa first name