Who can abuse Attack Speed runes?

with that level 1 dragon.

Junglers, and that's about it

Only jungle camps stand still long enough for Atk Speed to pay off

Junglers, ADC's, and AA reliant fighters/melee carries.

I like AS Quints for ADC's and AA fighters. For tank and AP junglers, I go with AS Marks (usually to get AP or Armor Quints).

Reasons: ADC's and AA fighters like to Auto attack and with Doran's providing lifesteal, it allows you to AA minions/champions more often to get more health back, it is also provides more expensive stats so to speak. You get 13.5% attack speed from Quints versus 6.75 AD if you were to get AD Quints a longsword will give 10AD for 360 gold meaning 1 AD is worth 36 gold whereas a Dagger gives 15% AS for 450 gold making each 1% of attack speed worth 30 gold. A little math reveals AD Quints are worth 243 gold and AS Quints are worth 405 gold. You still can get AD Quints if your Abilities scale rather well with AD and you feel that will give you more bullying potential. You can also get Lifesteal Quints (a little pricey) as they will help you sustain a lot more in lane.

In the jungle, most AP champs and most tanks do not scale off of AD for marks, and jungle monsters (besides dragon, baron, and scuttle) do not have MR so M-pen is not going to help you clear. So, Attack Speed marks are the best marks for clearing the jungle as an AP or tank jungler. Some champs I do end up using Hybrid Pen marks in the jungle as Monsters do have Armor so the mark is not completely useless in the jungle. But this is mostly for champions I feel do not need extra help clearing the jungle as they have a lot of AOE damage and I want more damage on them and they do not scale well with AS at all: Gragas and Sejuani are examples of this. Attack Speed would increase their jungle clears, and sometimes I use AS reds for them as well, but it's just something I've been experimenting with (also note that these runes are incredibly expensive so AS reds would be much more bang for your buck).

Some champs I always use AS Marks on in the jungle: as they all have some sort of interaction with attack speed; Nunu and Malphite are not so obvious but with Nunu, more AA means more free spells thanks to his passive and Malphite because his new W is active for 6 seconds, attack speed means he gets more AA's off within this time frame which means more damage. Champions that I don't always get AS on even though they are AP or Tank: (AD marks; they scale with AD on some abilities); (Hybrid Pen; they have no interaction with AS and have a lot of AOE to clear); because he doesn't AA when he clears more than once or twice (M-Pen Marks for Ganks; I just use AP Mid lane runes for him). There are others that I am not mentioning, I know, but this should give you a good representation of my reasoning behind why I put AS Marks on a lot of junglers and why I don't on others.

Hope that helps. Peace.

Its pretty viable on all these champions. There is others, but they are questionable and borderline to me.

AS runes don't provide much on small amounts, so they are best reserved for AS junglers who can run a near to full AS page without being oppressed/disturbed, while scaling monstrously at the same time as you can just ignore buying attack speed the whole game (since it caps) and focus solely on other offense options.

Any auto attack champ loves them. to name just a few.

You know how to counter atk spd? and / or