I think the answer was Verdana years ago but not so much today with higher dpi screens. Verdana was designed for CRTs around 800x600, with wide letter forms an

I think the answer was Verdana years ago but not so much today with higher dpi screens. Verdana was designed for CRTs around 800x600, with wide letter forms and kerning, to get ample spacing between glyph elements. It's the champion of readability in that format, but on a modern 1920+ display with subpixel rendering rather than an aperture grill, Verdana feels too big and clunky.