Like Oliver - it would probably top our 'boys names' list but as others have said it's just sooo popular (no.1 name) right now, which puts me off. You might not mind though.
Rowan - agree that it has become a girls name. How about Rohan?
Barnaby - love it but am of the 'Barnaby the Bear' generation. Trying to persuade my DH that it's a contender though.
Hugo - I don't like this, puts me in mind of sweaty overweight city bankers in pink shirts.
Warren - not keen though respect your family reasons for considering it.
Alternative ideas; Reuben, Toby, Gregory, Jasper, Fraser, Wyatt, Piers, Caspar.