I would vote for Feather light and middle weight (could be both 1 and 2).
First of all each of those have little bit another purpose.
Feather light is first of all for connecting stuff on the go or quick increasing of ports.
Use cases: meeting with client at work, when they can have a projector with anything: hdmi, DP, Mini DP; quick sd card reading (for large ones), connection through ethernet (when your router is not working properly) and so on. For me it is mostly port extension, one dongle for everything. I know some people use this stuff as stationary dock, but i think it is mostly because of price.
Middle weight: this is stationary dock for quick plugginng all your stuff at work or home (mouse, keyboard, monitors and the rest).
eGPU - for me it is still something other than dock, unless you need some extra graphic boost for handling multiple 4k monitors, like in case of acer dock.
Summing up: I’m for two dock’s -> one portable dongle and one stationary beast:)