Traction always wins if you have it, because traction provides positive evidence to all the important questions: Can this team execute, are there any customers who want this, can you reach those customers, can you get enough money from them, etc..

Vision is B.S. at this stage, because existence or lack of vision won't be what gets you to the next stage, and it's quite possible that your vision will change between here and there.

Everyone has customer references, so that's not interesting, unless you have a high-dollar product (e.g. selling to enterprise) and you have only 1-2 customers but they give you real money and say good things -- that's considered good traction if that's your target.

You'll also need to be clear on what you'll do with the money, what you expect those actions to accomplish, and in what timeframe. In short, seed/angel is either to get profitable or (far more common) a proper Series A, so there needs to be a clear concept of what you'll do to line yourself up for a solid A.