I'm assuming that you are wanting to see which is more effective at level 1
Well, lets look at a full set of flat AD Marks and Quints
Attack Damage
Marks = .95 x 9 = 8.5
Quints = 2.25 x 3 = 6.75
8.5 + 6.75 AD = 15.25 AD
At level 1 Jhin has 53 base AD
And his passive automatically increases his total AD by 2% (assuming that he has no other form of attack speed or critical strike chance)
1.02 x (53 + 15.25) = 69.615 Total AD
So we need to beat this in order to determine which is more effective.
Critical Strike Chance
Marks = .93 x 9 = 8.37
Quints = 1.86 x 3 = 5.58
8.37 + 5.58 AD = 13.95 Critical Strike Chance
Jhin's passive increases his total AD by +2% (base) and +4% per 10% critical strike chance
To my knowledge, this is rounded down, so this would only increase his overall AD by a total of 6%
1.06 x 53 = 56.18 Total AD
However, keep in mind that any additional AD purchased will be increased at a faster rate.
Lets also look at the other part of Jhin's passive. His attack speed scaling.
Attack Speed
Marks = 1.7 x 9 = 15.3
Quints = 4.5 x 3 = 13.5
15.3 + 13.5 = 18.8% Bonus Attack Speed
Just like with crit, I believe the bonus only scales per 10%, so it still only increases his overall AD by an additional 2.5%
1.045 x 53 = 55.38 Total AD
Based on these 3 calculations, at level 1, the flat AD runes give the greatest total AD.
However,
As I mentioned, your overall AD does have a better ability to scale with Critical Strike Chance and Bonus Attack Speed.
At level 1 you can not increase your Critical Strike chance any further without purchasing
400 gold
+10% critical strike chance.
That is an additional 4% total AD
1.1 x 53 = 58.3 Total AD
However,
You do have the ability to increase your bonus attack speed without purchasing any items in game.
With as few as 2 points in the Fury mastery you can boost your bonus attack speed up over 20%
1.07 x 53 = 56.71 Total AD
And you can then invest your gold into an AD item
350 gold
+10 AD
1.07 x (53 + 10) = 67.41 Total AD
Or
300 gold
+12% bonus attack speed
1.095 x 53 = 58.035 Total AD
However, ..
If you were to purchase a long sword with your AD runes you would have
1.02 x (53 + 15.25 + 10) = 79.815 Total AD
So, if you are looking for the best way to get the most AD at level 1, AD runes are probably the best option.
If you are looking for a slightly lower option that scales better, critical strike chance might be easier, but I personally think it is a little awkward, especially if you want to try and get 100% critical strike chance that game, without going over the cap, it's pretty much impossible.
I kind of like the attack speed route (even though I know that most people don't) because it also gives him mobility, and you CAN exceed the 2.5 attack speed cap and continue to increase his passive.
If you have even read this far, I kinda just wanted to try and go through the math.
I'm a little bored lol.
And if my math is wrong anywhere, I'm sorry.
I would like to note however, that considering how insanely complicated this passive is,
The AD scaling has not been changed since he hit live servers.
That is quite impressive if you really think about it.