When fully closed properly, both styles are a palava to access; much as we like to have them, however desirable they might be aesthetically neither would get a design award these days.
Carrying the Kelly with the flap open is not wise from a security point of view; carrying the Kelly merely fastened by the touret with the sangles hanging is not good for the bag.
A Birkin or HAC is convenient when used as on open tote; with the flap folded against the bag, the double handles do bring the bags to a close with some degree of security.
Is your question hypothetical or are there two specific bags under consideration? If so it would be interesting to know the colours.
Carrying the Kelly with the flap open is not wise from a security point of view; carrying the Kelly merely fastened by the touret with the sangles hanging is not good for the bag.
A Birkin or HAC is convenient when used as on open tote; with the flap folded against the bag, the double handles do bring the bags to a close with some degree of security.
Is your question hypothetical or are there two specific bags under consideration? If so it would be interesting to know the colours.