Another vote for the HP G2 Thunderbolt Dock. I wanted a simple solution and didn't want to be paying £250-£300 or so for a dock. I took delivery of the HP G2 dock yesterday. I'm running the 2019 16" MacBook Pro. My monitor is the Dell Ultrawide U3818DW.
On a side note, the U3818DW monitor is capable of supplying 100 watts to the MacBook via USB C, the problem was, on a single USB C, the refresh rate was locked to 30Hz.
Hooked up the dock, connected the monitor via Display Port. Under System Reports, the monitor is running at its native 3840x1600 resolution with the 60hz refresh rate. Under Power, it's reporting the full 100-watt delivery and I can also confirm that the ethernet port works and so do all the other USB ports.
I've got the 38" Dell hooked up to my 16" MBP with a single USB-C cable and it runs at 60 Hz and full resolution. Are you perhaps using a cable that only supports 30 Hz?