Running both is the common case
The two tools do not compete for the same slot on the page, and they answer different questions. Keep PostHog on the product, where activation and retention live, and put the Tiny Funnel tag on the marketing site and the signup flow, where the question is who arrived, how far they got and who paid. The scripts do not interfere, and the numbers will differ at the top of the funnel because Tiny Funnel is cookie-less and counts everyone who loaded the page.
The honest version
For a technical founder who wants the whole toolkit, PostHog may simply be the better answer, and this page would rather say that than pretend otherwise. The distinction is not quality, it is the question. PostHog is what you install when you want one tool for everything. Tiny Funnel is what you install when you want one answer, drawn on screen at log-in, with nothing to instrument first.
The short version
If you want a platform, PostHog is a good one and the free tier is real. If the only question is who converts, this opens on the answer and costs $10 a month.