I have mapleader set to ",", which has served me well.
I just realized I only use my left thumb with the spacebar, so the ambidextrous argument doesn't fly for me.
But I did realize space currently does nothing for me in normal mode. So I made it work like less/more, i.e., it pages the screen down:
nnoremap <space> <C-d> nnoremap <S-space> <C-u>