So right now I am in the process of constructing a new Rune Page for ADCs. Previously, I just used the page I used for all AD characters. 6 ArPen Reds, 3 AD Reds, 9 Flat Armor Yellows, 6 Flat MR Blues, 3 Scaling MR Blues, and 3 AD Quints.

Right now, I am deciding to try something like:

9 ArPen Reds, 9 Attack Speed Yellows, 9 Attack Speed Blues, and 3 ArPen Quints.

Or should I run Critical Chance runes instead?

Any thoughts and comments on how I should arrange my setup?

Are you getting 100% CS? As good as you think Armor penetration and attack speed scale into late game, the gold you get from CS with AD runes scales better.

This is purely champ specific, but for "general" adc's i personally run AD Reds, Armor yellows, Mag resist blues with flat ad quints. My main adc is sivir, so that is perfect. However, let's say you want an Urgot specific page, Arm pen marks might be a better route due to the fact that , and i say this lightly, "any adc who relies on abilities tends to need more arm pen", as opposed to lets say vayne who is 75% auto attack.

Runes are for early game, Items are for late game. AS runes are practically useless on an AD carry. Saying this as a 1600 AD carry thats currently on a tournament team with all 2ks. (So I'm not some random telling you what to do.) There are some AD's where this isnt completely terrible, but just in general, and for example. I have 3 rune pages for AD (one is super niche and doesnt get much play at all.) So the other two look like this. 9 arpen reds, ad quints, armor yellows, mr blues. OR ad reds, ad quints, armor yellows, mr blues. I use the second one on, Vayne, Sivir, and sometimes Cait. But both work well for all AD's.

The reason no one uses attack speed yellow or blues is because they're bad. The only good attack speed runes are reds and armor pen is way better. yellows are typically health or armor and blues are usually best at magic and magic resist.

If you're just starting on ADC, it's better for you to go the standard rune page: AD Marks, Armor Seals, Magic Resist Glyphs, and AD Quints.

It is currently the most used setup for all ADC. I personally don't like it due to you already stacking physical damage already so if you want to be a hipster I can give you insight of each offense runes you can use as well.

NOTE: I highly recommend you using Armor Seals and Magic Resist Glyphs no matter what.

Insight for viable runes

Physical Damage - As stated, the best optimal runes that every AD carry can use. It puts your base damage much higher, scales with your skills (almost every AD spell scales really well with AD), and allows you to farm easier. Simply so much benefits you can get with having more AD at start.

Armor Penetration - You take this if you want to do better trades with auto. Used to be popular until the game play shifted from passive to aggressive at bot. Still it is the alternative choice to take if you don't like having AD runes since you're already building AD. Do note that Flat Pen and % Pen are counter-intuitive with each other.

Critical Strike Chance - Having these will unlock the chance to score a critical hit which doubles your damage output. However it is very inconsistent and it is much better to have consistency rather than relying on luck factor.

Attack Speed - Least optimal but still can be used. Using these runes encourages longer fights but very rarely will you stay in a fight in the lane. You also can't optimize them as well unless you're going for the aggressive push.

I use a similar built for Vayne/kog and it works good but longest u dont miss cs, you are fine! But if you are having trouble with cs just got with AD quints.

I run AD Quints and Red, Armor yellow, attk speed blue.

unless im up against sona or someone with poke then i replace attk speed by mr.

For some champs like draven i would switch reds to armor pen.

arp reds are good if you are great at hitting cs and dont spam abilities(i rather take more q damage on ez than arp for autos)
taking 1 crit red is also an option to just laugh when it procs on a champ in lane phase, since 1 ad or 1 arp isn't major

you need the armor yellows, its vital in bot lane where you should be trading often

as for blues those are less important but mr is generally better than the little attack speed since it offers you more resistance for team fights

quints should always be ad imo, arp reds and armor pen masteries make up for it plus it would lower your cs potential even more

Guess I could use the page for something else. I already got AP, AD, and Support/Tank covered. Maybe a Chanpiom specific Rune Page or maybe one for Hybrids. Judging by the responses so far, I'll stick with what I got now as it gives the best of both worlds in a fairly balanced manner.