If you buy an SSD, it is a good idea to buy a much larger one than you need, because the SSD controller writes the data in a way that each part of the SSD will be used sooner or later. That reduces the write cycles of the SSD. Normal usage is not problematic, but at some kinds of usages, data is written on the SSD and overwritten very often. Twice the size of an SSD only means half of the write cycles. It is like buying the same car twice. Then you will only have to use each of the car half of the time and both cars will last longer. Of course with cars that would be too expensive, but for SSDs it might make sense.
My notebook has a 1 TB SSD at the moment, but I might need to buy a second 1 TB or even 2 TB SSD sooner or later, because I download a lot of stuff and I like to keep some important files on my notebook as an additional backup. My backup drives are all conventional harddrives and accessing them to often can reduce their life span. So I prefer to access those files directly on my notebook.
My notebook has a 1 TB SSD at the moment, but I might need to buy a second 1 TB or even 2 TB SSD sooner or later, because I download a lot of stuff and I like to keep some important files on my notebook as an additional backup. My backup drives are all conventional harddrives and accessing them to often can reduce their life span. So I prefer to access those files directly on my notebook.