Honestly I'm not fond of any of them, but - I'm not a fan of black with this either. Maybe if you had some meters ..and knobs that had more silver and/or white highlights, then black would be on the table. That said, I do prefer the higher 'values' so the darkest (olive) would be my pick if I had to choose - It's not bad. Do you have any other knob options? I'm not nearly as persnickety as most people here, but those knobs just don't look inviting to me.
I'd lose the 'paper in oil capacitors' schtick. For 1. Hardly anyone knows what that even means 2. The rest of us that do dont care. 3. It's a fine mic preamp. Let it speak for itself. 4. How about "with genuine 1% tolerance resistors"? Just kidding on the last one but it emphasizes the point.