What are the best marketing channels for B2B?

B2B marketing feels simple from the outside:

Post on LinkedIn.
Send cold emails.
Do SEO.
Run ads.
Build in public.
Go to events.
Start a newsletter.
Launch on Product Hunt.
Do founder-led sales.

But when you’re actually building, it’s hard to know what is genuinely worth your time.

Some channels look good because everyone talks about them.

Some look boring but bring real customers.

And some make you feel productive while generating almost nothing.

So I’m curious:

What marketing channel has worked best for your B2B product?

Was it cold outreach, content, SEO, partnerships, communities, paid ads, events, Product Hunt, or something else?

And what channel turned out to be a waste of time?