move-text
is a simple Emacs package that lets you move a line or region around
using M + ↑ and
M + ↓. It's not limited to plain text
buffers - you can move lines of source code around too.
In practice it looks like this:

I prefer to use Control + Shift with the up and down arrow keys, so my configuration looks like this:
(use-package move-text :bind (("C-S-<up>" . move-text-up) ("C-S-<down>" . move-text-down)))
Cutting and pasting a region is usually quicker, but for shuffling a few lines around this method is quick enough.