Pick as in which one would I buy right now?
HD-DVD hands down. Best bang for buck, doesn't have Sony's arrogant asses involved, and I generally root for the underdog.
As far as picking a (eventual) winner: I'd say neither. If I had to pick one, well, let's just say it's still Blu-Ray's war to lose at this point with the CE and Studio advantage, and overwhelming B&M presence.
Why would I buy a format I thought would lose you ask? I'm betting the war's going to take a good long time and I will have gotten plenty of enjoyment outta my investment by the time it's over