I originally got HD DVD due to price of players and the completeness of the format at the time. I had seen a few of the BD players on the market and thought they all had a ways to go before calling themselves a finished product.
Then I saw a buddies PS3 and demo'd it's BD performance. After watching 1 BD movie on the PS3, I bought a PS3 (20gig at the time) for BD playback only.
Since then, I have scooped up good deals on additional 2 additional HD DVD players (grabbed a 3rd one as a insurance backup) and got a 2nd PS3 (80gig) during the walmart 10 free BD's instantly in-store during the holidays.
So for me, it was all about incentives and price of players at first. Now it's about movie prices and deals.