An open-source keyboard for Android which respects your privacy. Currently in early-beta. - florisboard/florisboard
FlorisBoard is a free and open-source keyboard for Android 7.0+ devices. It aims at being modern, user-friendly and customizable while fully respecting your privacy. Currently in early-beta state.
Everything from grammar to spelling and even the typing style. It's really fast and direct, completely free. It uses AI to do all the work and works with almost every language.
I haven't used the Samsung keyboard in years so I don't know what the comparison would be. I do think that for the most part, FOSS keyboards lag a couple years behind Google, Microsoft, etc. This is one that looks promising, but is still a long way off from a “complete” app.
I guess it depends on how much you care about privacy. There are a number of private keyboards now to choose from, but if you trust Samsung (Google, MS, etc.) with your keyboard data then it may make it worth the upgrade in features