I have seen lots of noise about the Gulikit Hall Effect replacement joysticks online a few weeks ago, but few reviews. Yesterday Lon Seidman had a livestream of doing the replacement. It took a bit of time, but looks like they work pretty well. The only criticism Lon seemed to have is they were a bit more slippery than the stock joysticks.
Why It Matters
JoyCon joysticks are notorious for wearing out and drifting. The solution has been for you to send them in for free replacements. Nintendo has allegedly improved the wearability of the joysticks. However you still end up having to send them in for replacements every once in a while. These third party replacements should last much longer.