How exciting!
But I understand it's also not an easy choice.
Now, which colours do you like and which would work with your wardrobe?
Do you have the option to go to a boutique and see some colours IRL (like leather swatches, SLG, other bags so that you can get a better idea about colours/leathers)?
Since this is going to be your one and only B., I would keep it simple.
A nice neutral or a color that works with almost everything and that will grow old with you.
My first pick wouldn't be Black because H. does so many nice colours and you can easily get a black bag from another designer.
I would rather go for something more interesting, like Etoupe, Taupe, Etain, Graphite, Gold, Blue Colvert, Blue Indigo or Blue de Prusse. Or Raisin if you like a very dark purple.
If you like a bit more color and if you like red, I would recommend to have a look at Rouge H (classic burgundy red) or Rouge Casaque (bright true red).
There are so many options and since you are going to buy pre-owned, take your time to find out which bag will make your heart sing
.
Good luck!