I love long necklaces, and they are super versatile! Casual or dressy, very relaxed chic look.
I agree on the 10, only works when you have an open neckline; otherwise, it competes. I don't wear collared shirts anymore either! Hence I don't wear short necklaces as I mainly do round/scoop/ballet necks. But the 20, it works for all necklines! And for sweaters, I do a lot of sweaters in the winter too and love it with a long necklace. By the way, speaking of chunky sweaters, I just discovered Naadam during last winter's COVID lockdown... super soft cashmere, not expensive, super casual. I purchased a couple sets of the Boyfriend Cashmere Cardigan and paired it with the matching Cashmere Cropped Pant. It's casual wear, but not bummy at all (leisure wear can look really bummy fast, but this still looks pulled together while being super comfy). I really like it, so as FYI, you may want to check it out. Looks great with a 20 motif!
I vote 20! Looks really great on you. The WG works perfectly on you too. Did you get VA earrings? I have the WG MOP set and like it a lot. So glad you love WG too! I wish VCA would make more WG pieces. Congrats again! I'm so happy for you!