Alyce, that (NASDAQ:AMZN) stock really isn't all that pricey. I'll point you back to my original bull argument again for the details, but suffice it to say that Amazon looks historically cheap right now, despite the recent run-up. That's what happens when a company finally gets around to executing like it should, and then the market catches on. You start from a rock-bottom valuation and shoot back up to a decent one.

Alyce is right, of course, in her high-volatility argument. Some stock charts look like kangaroo playgrounds, what with all the bouncing up and down. A patient investor can surely make a serious difference to his or her portfolio returns by waiting for an appropriate market dip before buying in.

But then again, that doesn't always work either. Remember back in May 2005, when Google (NASDAQ:GOOG) looked so expensive at $250 per share, sitting on 120% or more of nine-month appreciation? Many of us held off then, thinking that some of those gains would have to come back off before the stock went skyward again. But that never happened, and Google stock is twice as expensive today.

You can tell similar stories about Apple (NASDAQ:AAPL) in recent times, or the early days of Microsoft (NASDAQ:MSFT), or even IBM (NYSE:IBM) in the mid-1990s. There are times when the boat is about to leave, and you just have to catch it before they cut the moorings and head out to sea.

That's where I think Amazon stands today. The company is firing on all cylinders, and while there might be occasional speed bumps in the road ahead, I think the Bezos gang has what it takes to stay on track. And there might be no going back.

Wait! You're not done with this Duel. Go back and read the other arguments, then vote for a winner.

Amazon is a Motley Fool Stock Advisor pick, and Microsoft is a Motley Fool Inside Value selection.

Fool contributor Anders Bylund is a Google shareholder who holds no other position in any of the companies discussed here. He would like to apologize for the excessive use of mixed transportation metaphors. You can check out Anders' holdings if you like, and Foolish disclosure is the ideal travel partner.