Well, I guess Newton is not officially compatible with Android yet. I have PhysX for Android, Windows, and Mac, but the iOS version is not released yet.
Newton going open source is not a good sign, because it means if you have a problem, you have to fix it yourself.
I know Bullet won this poll, but I think it would be the worst option of the three: Open source (=bad documentation and support), no corporate marketing campaign to convince people it's the best, and I am not familiar with it.
It's a tough call because PhysX means restricting the world size below what we have now, but my guess is people would rather have it, even if it's full of bugs, just because it has a nice logo.
Upper left at 0:07:
I guess I'd better start talking about THE AMAZING POWER OF PHYSX 3 since AFAIK Leadwerks will be the only major engine using the new version.