Albert Wenger at Union Square Ventures wrote a short and compelling post comparing the attractiveness in investing in a company with killer traction vs killer team, weighing in on the side of traction:

If there is real traction in the form of accelerating growth in customers or usage at non-trivial levels then that’s huge. Many companies never get there. I would pick that over an experienced team that has been at it for some time without gaining traction.

I agree, and think that the overwhelming majority of companies (not just most) never get there. Take one killer concept: web-based personal finance and two sites launched simultaneously by Wesabe and Mint. Both have garnered good press and reviews, but Mint has considerably better traction and product-market fit:

Without traction, a company is constantly slipping back in its tracks and wasting the energy it expends without moving. With an exceptionally strong (and expensive) team, it is possible to make forward progress,  but you are much more likely to spend more time, energy and money than you have. A little traction makes a strong team that much more effective.

Practically, this means that start-ups should measure traction in honest ways that discount the heroic and unscalable human efforts of star team members. If you’ve developed a corporate product and are running training sessions on selective sites, measure the activity of the subscribers that are not being trained – the activity rates of subscribers receiving training will be higher, but the human efforts being applied mask the fact that the product does not have the fundamental traction it needs to grow and scale unaided.

Bottom line: Take traction every time, and look for fundamental product traction that exists independently efforts of human effort and team members.