I like
Brendan a lot; I'd use
Brendon as an honouring name, though objectively I prefer
Brendan.
Brandon does less than nothing for me; like a merger between
Marlon and
Brando.
Brandon does seem a whole lot more modern than 1940s-1950s
Brenda.
Brenda,
Sandra,
Patricia ... and
Brenda is the drabbest of them all.