Generally a classic name tends to be one with a rich history but that has also had long periods of fairly popular or regular use.
So imo none of those is really classic apart from perhaps Isabel if using this original spelling (unless you are in France or Scotland where it is spelt Isabelle/Isobel respectively so those spellings may be classic there, I have no idea ).
Perhaps Georgina rather than the lovely but rarer Georgiana might also be considered classic. But if classic is definitely the parameter then of your options I’d vote for elegant Isabel.
However timeless Elizabeth (with the nn Elsie if wanted) would be as classic as you can get. And Margaret rather than very trendy Margot would be nearly as classic as Elizabeth (Margot could be a nickname too if wanted).
I do love the sound of pretty Genevieve (and its myriad of nicknames) but I’m not sure it’s really considered a classic as such, in the UK at least.
ETA: Audrey is retro cool now (in part thanks to Audrey Hepburn) but again, not really what I would call a classic. I realise I have said “classic” a lot but really it often tends to be very traditional names that have been popular historically- so Mary, Catherine, Elizabeth, Margaret, Sarah, Jane, Eleanor, Charlotte, Caroline, Emily, Anne etc