The (quite cheap) Lenovo Ideapads are quite good. I've upgraded my S540 with 32 GB of RAM (instead of the base 8) myself, it can receive a second M.2 SSD, and the first one is also upgradeable.
The only small problem is with the keyboard : the most used keys are completely blank after 3 years of use :)
The only small problem is with the keyboard : the most used keys are completely blank after 3 years of use :)