Transmission with additional features

The features include:

sequential downloading on macOS (Based on @midenok's work transmission-patches)
ETA badge for macOS Dock

How to enable sequential downloading on macOS:

Click on the icon of the torrent you want to download sequentially.
Check the Download Sequentially checkbox from the pop-up menu.

Alternatively you can enable it by:

Right-click on the torrent you want to download sequentially.
Select the Options tab (Gear icon) in the Torrent Inspector window.
Check the Download Sequentially checkbox on the Options tab.

The progress bar of the selected torrent will turn to orange.

How to disable the estimated download time badge on macOS:

Go to Preferences.
Uncheck the Estimated download time checkbox at the Badge Dock icon with section.