I use "darkblue" where I don't care for any particular scheme other than one having decent contrast between text & dark background. (In my own $ENV I have my own color schemes which is not as complete (due to incomplete syntax matching) as the ones included with vim, and I could not care less.) In any case I have found colors for word completion list & comment color (dark blue on black background) to be horrible in the default/no particular scheme (vim 7, 8), and not good enough under "darkblue".
When I use "darkblue", I have lightly modified some of the colors ...
...
" Removed custom syntax matching & associated highlight colors.
" black/grey: 0, 0c0c0c red: 1, fc3c4c
" green: 2, 0cdc0c/33ff33 brown/yellow: 3, fcfc00
" blue: 4, 4c4cdc/000020 magenta: 5, ac4cac/bc40bc
" cyan: 6, 3cbcfc grey/white: 7, dcdcdc/fcfcfc
"
hi Comment cterm=none ctermfg=5
hi Identifier cterm=bold "ctermfg=6*
hi logLevelNormal cterm=none ctermfg=2
hi logLevelNormalMess cterm=none ctermfg=2
"
hi logLevelWarn cterm=bold ctermfg=3*
hi logLevelWarnMess cterm=bold ctermfg=3*
"
hi logLevelErr cterm=bold ctermfg=1*
hi logLevelErrMess cterm=bold ctermfg=1*
" Normal completion menu item;
hi Pmenu term=reverse cterm=bold ctermfg=0 cter
+mbg=6
" selected item;
hi PmenuSel term=reverse,bold cterm=bold ctermfg=7 cter
+mbg=4
" scrollbar;
hi PmenuSbar term=reverse cterm=bold ctermfg=0 cter
+mbg=2
" 'thumb' of the scrollbar.
hi PmenuThumb term=reverse cterm=bold,reverse ctermfg=0 cter
+mbg=2
"
" Have not seen these in GUI in a long time.
"hi Pmenu gui=bold guifg=#dcdcdc guibg=#000000
"hi PmenuSel gui=bold guifg=#ffff00 guibg=#000000
"hi PmenuSbar gui=bold guifg=#ffff00 guibg=#000000
"hi PmenuThumb gui=reverse guifg=#ffff00 guibg=#000000
...