What’s the difference between a “good-looking site” and good web marketing?

When clients or teams talk about a “good-looking site,” we’re usually talking about subjective aesthetics: colors, layout, vibes - OR, is it just "stuff" the designer, CMO or founder personally likes?

But:

• Do we really know what percentage of visitors even notice or care about those design choices.
• We definitely don’t know how many of them like it vs just tolerate it.
• On the other hand, we can measure traffic, rankings, conversions, leads, sales, etc.

If you had to choose, what’s more important to you:

1. A site that looks great to you/the client, even if traffic and conversions are mediocre, or
2. A site that may be “just fine” visually but clearly wins on traffic, rankings, and conversions?

And how do you explain this to owners who are obsessed with how the site looks but don’t talk much about how it performs?