The search for a Buffer alternative almost always has the same trigger: the bill has grown without the benefit growing with it. That is the model, not the product — per-channel billing means the very thing you want, being visible on more channels, is what gets penalised.
For the DACH region a second point comes in that rarely appears in English-language comparisons: server location and billing currency. A US-dollar invoice from a US provider is not a deal-breaker for German freelancers, but it is extra friction — in conversion, in bookkeeping, and the moment someone asks where the data sits.
Streampost is built for that case: one price for every channel, servers in Frankfurt, interface and support in German, invoices in euros with VAT shown. What Streampost does not have is listed honestly above — most of all a permanently free tier.