I had the same question a while ago and I stuck with points.

This is how I look at it:

I can afford to spend a few hundred thousand miles to purchase first-class tickets. I cannot afford to spend 10K+ to do that. If I spend $100,000, 1% cash back is only $1,000. In this case, I'm ahead.

It really depends on how much cash back you're getting and how you plan to travel...