I bought this one. I had one before that was stolen along with the old MBP. It was one (these are everywhere on Amazon) that had two USB-C ports, you plugged it into the side, and it was kind of a port extender. While I liked it (for the limited use I got out of it in about a year), sometimes I had a little trouble making sure it was a snug fit, especially with a case on the body.
So this time I bought this Anker port adapter:
https://www.amazon.com/Anker-Adapte...adapter+usb+c&qid=1564809866&s=gateway&sr=8-8
I went with this one because 1) Anker makes a lot of good products, and 2) this takes up just a single USB-C port and doesn't have any issue with fitting along the side. Ironically I got a MBP model with four ports, so the extra port saved is less of an issue. But it might be for people with the 2-port models.
You can find cheaper adapters with fewer port options, but I would recommend getting one that has everything a sane person might use. There are plenty of reasons for me to use USB 3, HDMI and the SD card slots. I don't know whether one model has all the above plus ethernet, but that's the only other major port I can think of needing. If you can find one that does all that for $50 or less, go for it.
Also, so far I'm liking a SanDisk dual USB flash drive that does USB-C and USB 3:
https://www.amazon.com/SanDisk-128G...sh+drive+dual&qid=1564810228&s=gateway&sr=8-3
I got one before that swiveled. It took maybe two or three times using it for me to push it too hard or something and basically break it. Once I figured out that I had to push the USB-C end in *all the way* to actually insert it, it works great. Also showed me how much slower USB 2 ports are than these ports on the MBP.
