Best customer attribution tool fro B2C SaaS?

I run a B2C SaaS startup (DataLemur.com) and am struggling to figure out user attribution. I get tons of users from LinkedIn, Twitter, SEO, email marketing, and word-of-mouth – but can't accurately attribute what channels lead to customers, and what channels lead to revenue.

I've tried Google Analytics – but it doesn't seem good enough. I tried setting up MixPanel, but it didn't help me get a clearer picture.

I UTM most of my links, but still can't make sense of the customer journey.
Any ideas? Am I just using GA4 wrong?