Choosing how you'll get your message out to the world (and eventually get paid for it) is a big decision. This article will help you decide which content medium is best for you. I'm going to argue the case for each of the main 3 content mediums: the written word (blogs), audio (podcasts) or video (YouTube).
Tip: Focus on Just One at First
In a perfect world, we'd all have a large, active presence across all three mediums.
No matter what your message is, there are people who would prefer to consume it in either audio, video or the written word. So, being on more platforms allows you to reach and help more people which is of course, ideal!
No matter what your message is, there are people who would prefer to consume it in either audio, video or the written word
BUT, in reality, we can't properly utilize each medium right out of the gate. It's most effective to focus on and grow one medium at a time and then eventually expand outwards to other platforms.
This decision is hard because it seems that all the big names in every space are using all three mediums at once.
However, most of them started with just one and then used that audience to increase the speed of growth for their other platforms.
Pat Flynn of SmartPassiveIncome.com for instance used his podcast to grow his website and email list. He then used that to grow his large YouTube channel extremely quickly as a result.

Seth Godin used his blog (Seths.blog) to catapult the success of his books and podcast.
And Tim Ferriss used his wildly successful podcast to send traffic to his blog and grow an email list that essentially prints money on demand (his 5 bullet Friday is one of the few email broadcasts I genuinely check my inbox for each week).
Each medium has its own unique set of skills you need to develop. There will be a slow growth phase as you start followed by an exponential spike in growth once you reach a critical amount of traction.
James Clear describes this best with his concept of "The Plateau of Latent Potential."

If we're dividing our time equally between 3 mediums, the collective time before we really crack into the growth potential will be multiplied by 3 (all things being equal).
Instead, we should focus on one medium first and THEN use that audience to help expedite the growth of the others (if you choose to expand to others).
There Is No Universal Best
This article could be extremely short if there was a one size fits all answer. There isn't.
You can find wildly successful people in any of the three mediums. The question you should be asking instead is, "which platform is best for me?"
For a fun little reference, here's what members of one of my favorite affiliate marketing Facebook groups said when asked which is working best for them.

Small poll in an affiliate marketing group (Automation Nation). Blogs are the winner of the three based on this little poll.
Blogging took the lead in this small sample, but that doesn't mean it's right for everyone.
Let's start by comparing each medium in key areas: conversions, engagement, ease of creation and ease of growth.
Best for Conversions
Writing (Blogging)
Blogs have limitless potential for adding calls to actions. You can sell products, collect emails and drive any sort of desired action at the same time on the same page. The only downside is that readers can develop "banner blindness" so conversion rates might actually be lower than on audio or video but total conversions is typically higher since you can have many more impressions.
Audio (Podcasts)
I've purchased many products from podcasts and I totally expect an ad or two during a show promoting something. The downside is that visitors will have to do a bit of work to go and act on the call to action. Most blogs are sure to receive some sort of branded, unique offer code that will attribute sales to them. Conversion rates will be through the roof when people do put in the work to convert but the total number of impressions will be the lowest of the three mediums..
Video (YouTube)
My experience has been that people don't appreciate being sold things on YouTube as much as they do on other mediums. You can link to products in cards (if they're on your owned and approved website) or in the description.
Best for Engagement
(Video) YouTube
Video gets by far the most engagement of the three mediums. Viewers can leave comments and typically can expect some engagement on their comments extremely quickly. Real discussions happen in the YouTube comment section. The downside to this is filtering out trolling comments but the reward is typically worth the price.
Writing (Blogging)
Popular blogs can receive a good amount of comments but there is a mild barrier to entry and a longer delay between comments and comment interaction.
Audio (Podcast)
Besides reviews, podcasts don't have a good way to engage with episodes.
Easiest to Create Content
Audio (Podcasts)
Although some expert podcasters will argue this, I believe podcasting is the easiest sort of content to produce. You can create high quality podcasts on a very low budget. As you scale, you can upgrade your gear and increase production quality but the barrier to entry is very low and you can bang out dozens of podcasts in a very short amount of time.
Writing (Blogging)
Creating blog content isn't incredibly difficult. The learning curve isn't incredibly steep and once a repeatable process is created, you can create a great deal of content in a little amount of time.
Video (YouTube)
Unless you're a natural at editing videos or have a rough style that requires little to no editing, video content can be a huge time suck.
Easiest to Grow an Audience
Video (YouTube)
YouTube is by far the fastest medium to get views. YouTube doesn't play favorites quite like search engines do and they'll gladly send huge amounts of traffic to new channels if they create great content and follow some basic best practices.
Writing (Blogging)
Although it can take awhile to grow domain authority and rank in search engines for competitive terms, bloggers who understand how to perform proper keyword research can start getting visitors much more quickly than people might think.
Audio (Podcast)
Unless you hit the "New and Noteworthy," or "What's Hot" sections or have an existing following, growing your podcast audience is a slow march. Episodes can be created quickly but getting people to listen to them is a different struggle.
Why Blogging Is Best

Why Video Is Best

Why Audio Is Best

Conclusion:
There are pros and cons to each medium. The one you choose should be based on your unique personality and which medium will allow you to reach the most people as quickly as possible. Choose the medium that you like best and remember that you can (and should) expand to other platforms later.
Join the
21 Day Blog Challenge
If you've chosen blogging, this is what you need to get started!