Most of you already encountered a big problem: the limited internal memory space of Galaxy S5, that is usually around 6GB free for a standard 16GB smartphone. But, due to it's microSD slot, it support up to 128GB of external memory, that can be used for many purposes, including for moving installed Android apps & games.
So, what are the best available microSD cards for Samsung Galaxy smartphones?
128GB MicroSDXC Class 10 UHS
Also, you should take in consideration the speed of this microSD card: up to 30MB/s - that means a short delay for starting apps that are installed on your card.
64GB MicroSDXC Class 10 UHSI think the best microSD card for a Galaxy smartphone is SanDisk Extreme Plus 64GB MicroSD. It's great advantage is the transfer speed: up to 80 MB/s read speed and up to 50 MB/s write speed.
Of course, you can find many other cheaper 64GB microSD cards, but the main problem will be their poor performance. For example the installed apps & games moved on your card will freeze or start with a huge delay that will make you very nervouse sometimes.
32GB MicroSDXC Class 10 UHSSanDisk Extreme Plus 32GB MicroSDHC is the best choice for people that don't need too much external memory space for their smartphone. Also it support transfer speeds up to 80MB/s and it's perfect for moving installed apps and games.
Update: June 2nd, 2014Samsung Electronics brought to the market even a little faster microSD memory card tha has 64GB storage capacity and it can achieve transfer speeds up to 90MB/s: Samsung Electronics 64GB PRO microSDXC.
A 16GB or lower microSD card isn't recommended for a Samsung Galaxy smartphone, you would waste your money if you'll buy a card that don't have at least 32GB.