In general, it has to be a "regular" laptop, and not an ultrabook. The ultrabooks have gone to soldered in RAM and SSDs to save space.

Try looking at ifixit for repairability scores. They take the laptops apart and show you the internals on the reviews they do. https://www.ifixit.com/laptop-repairability

Of course, cross reference the repairability score with your desired performance and price. Pick any one.