The old conundrum, I guess it depends on in your case what you intend to use the laptop for. I would suspect for work, and running apps or programs, not so much games.
As rule if you intend to run a lot of programs all at once, switching between them while you work I would say memory, saying that 4Gb is sort of ok anyway.
The only good thing about for example fitting a M- Sata SSD would be faster loading and saving times/ and boot up times of the OS.
I will use it for college for the most part , using programs like VMWare, Microsoft office, and Packet tracer. Lastly moderate gaming during downtime.