Here lie personal reviews of my mechanical pencils, and maybe the occasional one I don’t own.
I use them for writing rather than drafting, so prefer 0.9mm versions and B or 2B leads. For pencils with a firmness setting, I use cushioned. Most of the work is text, maths and occasional diagrams.
Initial impressions come from tests on unruled white paper on a stack in a clipboard.
I often buy from specialists Cult Pens but am not affiliated with them in any way.