Keyboards are an often-overlooked component of your phone. Many third party keyboards could potentially transmit data back to third parties, meaning they're digital keyloggers. This is especially true for Samsung phones, who have their proprietary keyboard as the default and could transmit data back to corporate HQ.
The trick to finding a good keyboard relies on several factors:
The reason I put that first point where it is is because I always turn autocorrect off on every device. I'll list my top keyboard recommendations starting with my top pick, and all but one can be found on F-Droid.
OpenBoard/HeliBoard
OpenBoard took everything I love about GBoard, removed the tracking, and is open source. It hasn't been updated in a long while, though, which is why someone forked it into HeliBoard. If I'm writing a new page from my phone, odds are it was while using HeliBoard.
Another great open source keyboard. This one gives you a full desktop QWERTY experience (has to be configured in Settings). It's best used in conjunction with Termux. Just be careful, as this one hasn't been updated in over 4 years. Other drawbacks include inaccurate typing and the lack of a word suggestion bar, so if accuracy is important you either need extreme patience or maybe stick with HeliBoard. That said, I do have uses for this one.
The standard AOSP keyboard
This is the one not found on F-Droid. If your phone doesn't have GBoard installed, it will have this one. The AOSP keyboard, as the name implies, is open source. The biggest drawback to it is the lack of a dedicated number row.
Simple Mobile Tools was bought by some adtech company. Most of those apps have been forked to the Fossify project, and Fossify Keyboard is a very great AOSP-like keyboard.
Another feature-rich open source keyboard. The word suggestion bar isn't working right even on the Beta build, and my own typing is far more accurate on HeliBoard.