for a gaming laptop a 128gb is not big enough to store all of your games on it
ssd is better and faster than hdd
with ssd windows will boot to desktop in 5 to 7 seconds
a 120gb ssd can hold the os and a handful of games.
With lower ssd prices, 240gb is probably a much better deal.
It can hold a good number of games.
Only if you have many many large games or will store large files such as videos might you need more.