I have two basses and a 'cello, and started on another bass that I sold to get my second. On none of these instruments does the open top string (G for the basses, A for the 'cello) make as good a sound as the others or as any fingered note. Is this a frequent characteristic of stringed instruments? When I started on viola, many decades ago, I used a gut A, so that the open sound was fairly mellow, but these had rather a short life before they broke.

My G on the bass is good (so my teacher tells me), I have spirocore strings.
My A as a bad wolf in it (on the open A), that is the bass of course, not the string and she's getting me a 'wolf eliminator'

It may be the strings. A couple of years ago we took my son and his cello to Robin Aitchinson in Ely for a string trial. After asking my son what he wanted from his cello he tried lots of strings and combinations to find the best for his cello. He now has 3 different types of string on his cello with the A & D being Larsen soloist. His A string sings out and the whole range on the cello sounds great.