35 in Togo would be my pick. Epsom would work too. Having been down this path, I have to say that for me, a Birkin was not an ideal "everyday" diaper bag...better as a special occasion diaper bag. There was just too much going on to have to worry about it; the lack of a shoulder strap and its weight can be cumbersome. Ziploc bags were key. Good luck!
I second that~!