This works good for me - monitor sleep on the Dell displays I use work properly. If you want one that down the road can do 4k @ 60hz, this is not the one for you (but as I'm doing 1080 it is a moot point for me.)
https://www.amazon.com/CHOETECH-Thunderbolt-Compatible-MacBook-ChromeBook/dp/B01LYS3Q5A
IIRC they have a newer version that is HDMI 2.0 and supports 4k@60, if by chance you are looking for that future capability, even tho now you only need something to support 1080.