If I were trying to create a capsule collection, I would want to fill these needs:
Daily non-work bag, can carry everything I need for a day out, say, exploring a city - for me this is Kelly 28. Black or Gold (I have both). The Kelly 28 is a perfect bag IMO. The Bolide 31 is also a GREAT option.
Work bag - can carry a laptop - honestly H falls down here but I'll say Garden Party, also Black or Gold (I have both).
Non-formal bag for evenings, dinners, or days when I carry less - Kelly 25. I would say a jewel tone here - raisin and Vert Cypres do the job for me.
More formal clutch - Medor or Egee (that's as formal as I get). Maybe Black Box, or break the rules and do a shiny exotic.
Cross-body mini bag - Evelyne TPM. You can do a bright color here. I wear my Gold and BE most.
Larger cross-body bag for errands, dog walks, etc: Evelyne 29. Maybe a nice neutral here (mine's black, but I have Noir and gold in almost every bag, I'm very boring).
Running around "nicer" mini bag - Mini Bolide. As much as I love the Mini Kelly, this is a more useful bag IMO.
Tote: Birkin 30 or 35, take your choice. One of both is ideal!
To add to this and to edit more specifically, for me an ideal only-H capsule would be - limiting it to 10 because any more than that can't be called a capsule IMO:
1- Kelly 28 retourné, Noir or neutral
2- Kelly 25 sellier, neutral/jewel tone/bright/exotic
3- Kelly mini or evening clutch like Egee or Medor (depending on your evening needs and whether you can use a mini K at night), Noir Box or alli/croco bright
4- Birkin 30, Noir/neutral/jewel tone
5- Birkin 35, Barenia/Noir/Gold
6- Evelyne TPM, any color, mini Bolide, or mini Lindy (crossbody runaround)
7- Garden Party 36, neutral (work or mom bag....if you don't need either, sub in any larger bag like a K35, Victoria, Steve, Initiale, Wallago, etc.)
8- Bolide 31/35/37, any color
9- Evelyne 29, any color (if you don't need a crossbody bag this big, you could substitute the TPM and choose a different mini bag above)
10 - *Bag #10 should be something different or funky - a vintage, or a really big or really small bag depending on your needs and taste. Maybe a Passe-Guide, or a Picnic version of a bag you love, or a Lydie, a Drag, a Cargo version, or a big unlined bag like a large Pico, Double Sens, or Massai. Or a Toolbox!
With these 10 bags you should be able to cover just about any situation IMO. (Yes, I left out the B25 because although I like it, I do not find it functional in a practical way. The smaller bags with straps work a lot better, again, just IMO. Same with smaller Picotins, for me, they are cute but not functional. Also IMO, I would stick with the more durable leathers for all daytime bags.)
What should every *collector* have, as opposed to a practical capsule? That's a whole other thread!!