Will most investors consider a prototype only?

It's usually not enough. Value is derived from the users (traction) and not from the prototype itself. It's recommended to approach investors when you have either 100 paying customers or 1000 users.

Here's some further advice: https://www.youtube.com/watch?v=9jBzNeLyGcA

What level of investment do you want? You sound early stage, possibly approaching Angels for seed funding?

so traction's less relevant when you're at discovery stage.

Use a tool like QuickMVP to prove market need and interest.

It's really going to depend. I've raised institutional capital off a PPT before, however I had three things going for me:

1) West coast VCs for whom a smallish seed round wasn't that big of a deal

2) I was on-trend - there's a fashion element to VCs. A lot of them rush into hot areas and will put down a few bucks because they missed the boat on the company that's defining the space. While they may not go into a direct competitor, if you're operating against a thesis that's being validated by a hyper-growth startup it may be enough for a VC to think your variation may achieve similar results. At this stage it's almost easier to not have results to stand in the way of painting a vision.

3) I had a moderate amount of success previously and had a solid technical cofounder. As a result they felt they could bet on a team in an emerging space with not too much money at stake.

I think the less you have of these items the more traction you'll have to show.

Thanks for the answers so far. What if it is actually a fully complete project instead of a prototype? Does that make any difference or is it still a traction needed thing? The reason I ask is because this market is already proven but this product puts a unique twist on it that does not exist. Thanks again.