Speed versus capacity
An NVMe SSD loads the system and games several times faster than a hard drive, so pick an SSD for the operating system and your programs. An HDD still makes sense only for a large archive, where the price per terabyte matters most.
How much space do you need?
500 GB is enough for an office machine; for gaming choose a 1-2 TB NVMe, because a single modern game takes 70-150 GB. In our configurator the NVMe filter is on from the start - it is the most popular choice.