What should I run on quints?

http://lolbuilder.net/runes/popular

You can see popular rune pages by diamond+ players here which is how i chose my rune pages.

AD and AP quints are imo the more general picks for two different rune pages with armor pen/magic pen to create your first two rune pages.

armor yellows, MR blues.

depends on the role and/or champion and your rune marks

For generalized AD? If you're talking about like melee champions, I suggest flat AD or armor pen and having your marks be the opposite. If you're jungling, attack speed quints with attack damage marks. If you're playing ADC, same thing as AD jungler. Maybe throw in a single crit chance mark.

If you are talking ADC, Attack Speed is probably the best. It really depends on the champion though.

Standard Ad I would say flat AD quints depending on the champion. Combo or ability based champs like Graves or Rengar benefit from flat AD, while champs that deal damage mainly thru auto attacks like jinx, vayne, or AD kog'maw will benefit from attack speed quints quite a bit more

ad reds, armor yellows and mr blues (can be scaling) and atk speed quints for easier last hitting.