6.12 magic pen or 11.88% attack speed? I love 
and I'm trying to decide which runes would be better for her.
Also would it be better to have 7.02 Armor or 56.16 health?
Currently I can only get tier 2 runes, I don't have anywhere near enough to buy tier 3 ones. I'm still only 24, I think I begin working on getting tier 3 runes once I hit 30.
Leti the Yeti3 votesso... no one at some point told you tier 2 runes are noob traps?
Acidic Puddle2 votesNever get tier 2
SlackerboyTC2 voteseven though t1 and t2 runes are cheap now I would avoid buying them and focus on getting champions, no point in buying runes then realizing a few levels later that you dont want to play kayle anymore
Theads1 votesBetter than using nothing right?
MrBuffington1 votesit's a waste of IP though; with the price drops, if you want something i'd probably just buy T1 runes since they're so much cheaper, and the benefit to T2 is fairly small IIRC. I don't think there's any real need until you have access to T3 runes (also they usually do rune sales throughout the year, unfortunately you just missed one :(... there might be one later in the year or at the start of next season though). You can always outplay people mechanically regardless of your rune set up, the runes just make things a bit easier.
As for your question, I'd go with attack speed; Kayle's passive already shreds resistances, for the most part two attacks give you more than the benefit of the magic pen. imls (he's a high elo player and coach) recommends attack speed seals (the yellow runes) too, instead of a defensive rune, but that's if you're playing pure attack speed Kayle and you seriously want to optimize everything. If you're going for a defensive rune though, I might favor resistances because Kayle has a heal; your heal is going to heal the same amount of health regardless of how much health you have (unless you're at max), where resistances makes every point of HP you restore that much more difficult to take off. Then again, Kayle's ult makes her invincible, no better resistance than that, which is again why going for attack speed instead of a defensive rune is probably optimal.
EDIT: here's a video of imls coaching a Kayle, including runes and such (he words things pretty aggresively which might make him come across as toxic, try to ignore that :P):
https://www.youtube.com/watch?v=4WOYpP4cytM
also here's RiotPhreak explaining some rune choices, he has a couple of videos on his channel, here's one of them:
https://www.youtube.com/watch?v=GgBhSnIt4RM
best of luck
Duke Anax1 votesE does a lot of hybrid damage, so you should get hybrid penetration actually.
You don't really need AS runes, because that's the first thing she buys 
Peel Your ADC1 votesI think buying runes that make you farm more efficiently is the biggest speed bump many Kayle players struggle with. She needs the money to get her Nashors and Runnans, but won't have the OP damage (yet) to get kills on her own unless the enemy is really bad. So getting to 140~ cs as fast as possible is your goal.
Does hybrid pen help you with killing minions, even under tower? My personal decision is getting a lot of flat AP, some armor runes and AS marks. MR could be ignored because anyone who does enough magic damage to warrant them doesn't out-trade Kayle, unless some ass-hat took Leblanc top.
USG Morta1 votesi run hybrid pen reds, armor yellows, ap blues, and as quints. i understand that my page is rather expensive so for a cheaper and more reusable set i would suggest as reds, armor yellows, ap blues and quints. it gives a more ap but no pen and less as, so like they said, i'd go straight for the stinger with this setup.
Vauren1 votesI wouldn't worry about tier two runes, but if you must, I'd go with attack speed over magic penetration and armor over health. You could always go for magic pen quints in place of marks or vice versa. If there aren't hybrid penetration quints I'd go attack speed quints and hybrid pen marks. Armor seals for sure. It will mitigate more than the health will provide over time.