I'ved tried several third party keyboards (my favorite being Flesky), but I always end up back with the default Apple keyboard. 3rd party implementation is still buggy, still poses a privacy concern (albeit mild), and I've honestly never had an issues using the stock keyboard.
pretty much agree with every thing. The only concern is that the privacy risk is mild only if you believe that the vendor will not be malicious with your data and that they won't get hacked to the point where the hacker can have their way with your device. Remember that you have explicitly grant the keyboard vendor full access to your device. I too have decided to stick with the stock keyboard. Granted, I have given these rights to Apple. For now I trust them with my data and at least I am not exposing myself to multiple companies that increase the chances of a breach.