What is the most consistent source of high-converting traffic?

Its a bit of a catch 22 becuase you should never rely on an 1 source for traffic. You should always have a multi-pronged appraoch especially online where things can change drastically within 6 months. 

Your currently seeing a potentially major paradigm shft in google search where AI results are shown at the top of the serps. This has had some pretty serious repercussions on those who depend on google search/SEO for their main source or only source of traffic which is crazy imo. Those who were relying on it are learning that lesson the hard way like I had to many years ago.

I can attest to getting hit myself with every google update and that sometimes its had a major impact. Back in 2011 I had a site that i was completely dependent upon for income bringining in around 10-15k a month which was all based off SEO I was doing. And then the Panda update hit me hard. My income for the site 3 months later was around 500$.  I spent the better part of the next 12 months trying to get it back with no success and sold the site.

Upon reflection i realized all the mistakes i had made 

1)no email list 

2)no socials 

3)not enough of the right kinds of links that actually bring in traffic rather than just for boost in the serps like via guest posts 

4)no paid traffic sources were tested.

There is no 1 perfect place or strategy and they all change in time so you need to prepare.

These days i focus on paid traffic sources more than anything else. Its the most reliable by far imo although it has its drabacks also. Prices can change for the ads you are running, Ad platforms disappear over time or change for the worse. There is always the possibility of clickfraud. Restrictions on ad networks for what you can promote may also change. 

The crypto space is prime example of that. You used ot be able to run ads on facebook back in 2021 but in 2024 they get flagged along with any somewhat political ad.

As a good marketer you should always know have multple ways to rearch your target audience. 

Even offline ads can work. I've run billboard ads before that have had some success.

Its like Dan Kennedy said before. 

The most dangerous number in business is "one," emphasizing the risk of relying on just one client, source of revenue, or method