EDIT: OOOHH You're asking for single stat pages. My bad. Ignore what I wrote below if you want.
https://www.reddit.com/r/leagueoflegends/comments/345u2r/gold_value_of_almost_every_tier_3_rune/
If this is legit then
The highest value rune page at level 18 is 9 scaling AD marks, giving 758.16 worth of AD, 9 scaling health regeneration seals, giving 641.52 worth of health regen, 9 scaling mana regeneration glyphs, giving 648 worth of mana regen, and 3 scaling mana regeneration quintessences, giving 777.6 worth of mana regen. A total of 2825.28 gold.
I believe those are gold values and not saying scaling AD marks give 758.16 AD.
Also this page sounds less efficient on champions who don't use the stats (like mana on manaless).
I dunno. Interesting question.
I've heard though that the two most generic rune pages are:
9 ad marks
3 ad quints
9 armor seals
9 mr glyphs
and
9 magic pen marks
3 ap quints
9 hp/lvl seals
9 mr glyphs
So it sats AS marks and quints are the most valuable non scaling runes of their type. Maybe a full AS page? I'm only guessing and don't know.