New answer for an old question.
Mintstick from Linux Mint is the quickest, containing two separate gui tools, one to format an USB drive ("USB Stick Formatter"), one to write an image on it ("USB Image Writer").
To install it in older Ubuntu
sudo add-apt-repository ppa:tsvetko.tsvetkov/trusty-backports
sudo add-apt-repository ppa:tsvetko.tsvetkov/xenial-backports
sudo apt-get update
sudo apt-get install mintstick
For Ubuntu 18.04, until a newer version is launched along with an Ubuntu 18.04-based Linux Mint, download latest version 1.3.8 from here.
Open a terminal at the location of the download and do
sudo dpkg -i mintstick_1.3.8_all.deb
Install the missing dependencies.
If needed do
sudo apt --fix-broken install
then do again
sudo dpkg -i mintstick_1.3.8_all.deb.
Run it by typing "USB Stick Formatter" in a launcher - or
mintstick -m format in terminal.
In case that cannot be installed on your system, a good alternative is
gnome-multi-writer. It is able to format a stick before writing, but cannot simply format (without writing anything). For that, one can use "Disks" (gnome-disk-utility), which is a bit quicker than Gparted or the KDE Partition Manager.
If the usb stick already contains a live Linux, it is a bit trickier: first, select "Format Disk" from the top right corner (NOT "Format partition" ),
then select "Partitioning: No partitioning".
And only then select Additional partitioning options - "Format partition" , FAT, Next, Format.