Mobapad M6 HD
https://www.youtube.com/watch?v=0e3XMAXZ4Go
Some pics I borrowed from a reddit post:





They fit in tightly on the Switch, no looseness after you slide them on. It has two interchangeable d-pads that feel great. Hall effect, true analog sticks with a choice between a rounded base or an octagonal one via interchangeable face plates. The right analog stick is properly placed to the left of the face buttons so it doesn't get in the way like a certain other joy con replacement I tried. The shoulder buttons feel great. The back buttons are placed low so you don't accidentally hit them very often. You have full access to the USB connection on the bottom since it's not a shell that surrounds the whole system. It's ergonomically comfortable, but doesn't make the Switch feel too big. It retains ALL joy con features. Rumble, gyro, and amiibo scanning.
The thing came in a very high quality cardboard box and was extremely well packaged. The thing's great.
Now, if you only care about getting a joy con with a great d-pad, I could also recommend the Hori d-pad left joy con replacement officially licensed by Nintendo. You can even get it with a cool, Zelda skin. The d-pad on it is perfect, the ones on the Mobapad M6 HD are great too, but I think this one beats them by like a hair.