After many, many games as Kayle, and many build/play-style adaptations, I've settled on one that has been working very well for me.

This build has three stages. Early game is all about consistency and lane presence, staying in your lane and dishing out cheap (mana-wise) but significant harassment. Mid-game, you'll have a good amount of burst, so you can buy free kills while remaining a great support champion. Finally, the focus in late-game becomes turning Righteous Fury into a deadly team fight ability (that's right, I said Righteous Fury), while maintaining the burst and support from before.

I only included 4 items in the build because there are several viable 5-6 options, all of which focus on improving Righteous Fury.

Also, the stat section apparently doesn't include your talents in the calculation. With this setup, your CDR at 18 is just over 40% (the 1 CDR@18 rune puts it over the top).

If you think the build is bad, I only say don't knock it 'till you try it. It works very well for me, and if you play it right, it should do the same for you:

(The 4-11-7 record was in a game where 2 teammates assumed that I was playing support and without checking, decided that the game was not worth playing, so they fed intentionally.)

The key to this build is having a solid early-game, which means having a strong, sustained lane presence early on. Righteous Fury is the ideal ability for this. Its splash damage makes it a great farming ability, while the range gives you decent harassment/harassment-avoidance and the cost is low enough that you can pretty much use it whenever it's up because of your mana regen. If the opportunity to gank arises, by all means go for it, but don't force yourself out of the lane early on by taking unneeded risks. Ganks are great, but your early game should be all about consistency, so all you really need early on is to stay in the lane farming and harassing. Don't get me wrong - you need to harass your opponent as much as possible, but only do it as much as you can without losing your dominance.

DON'T USE RECKONING AS YOUR PRIMARY HARASSMENT. Until you get a little bit of AP and a couple ranks of it, the cost:damage ratio is way too high for it to be worthwhile, even against squishies. You'll run out of mana way too quickly and lose your lane presence. Only use Reckoning when you're going for a gank, you need it for you or your lanemate to escape, or it will force an enemy hero out of the lane. The only time you should use Reckoning as regular harassment is when you're at full mana or are about to recall. If you use it properly and position yourself well, Righteous Fury can provide enough harassment in the long run to force enemy heroes away, or if they're stubborn, for you to step up with a Reckoning/Ignite/Righteous Fury and kill them. Patience is the key.

So overall, your early game should consist mainly of popping Righteous Fury whenever it's up and attacking creeps at range and sneaking in cheap shots on enemies whenever you can get away with it (remember, only use Reckoning in the cases I mentioned above). Use positioning and bushes to your advantage, and if you can manage it, pull aggro with your harassment in a way that makes minions chase you without being able to hit you. It's a bit tricky at first, but it's one small thing that over time can push the lane to your advantage.

Use Teleport if you need it for fast travel, but it also makes a nice escape combo with Intervention if you're being killed by someone without a disable (I call it the Batman Maneuver).

Also, stay out of melee. I generally hide in the bush between Righteous Furies, especially if an enemy has low health, because if they take one step too close to you, they're dead. >:)

To start with, buy a Meki Pendant and 2 health potions. The mana regen will be huge for staying in the lane and letting you use Righteous Fury without hesitation. (TIP: A good way to save your health potions is, if you're missing health and have full mana, use Divine Blessing instead of a potion.)

If you can line it up properly, wait until you can afford boots (upgraded boots preferably) before recalling. Base your boot choice on who you're against, but most of the time I prefer the Merc Treads. Pretty much if there's even one significant CC'er on the other side, they're worth buying, and obviously if you're laning against a CC'er or a caster, they become that much better, giving you a good bit of survivability and thus more lane presence.

The next item to get is the Hextech Revolver, as it boosts your AP a good amount (making Reckoning actually worth the mana) provides a nice bit of spell vamp that will give you great healing over time with the Righteous Fury splash damage, enough that you should be able to keep your health up through harassment and some creep damage easily, as well as giving you that slight edge should the opportunity for a gank arise.

At this point, you can either finish the Hextech Gunblade or the Fiendish Codex, depending on how the game is going and which suits you better. The Gunblade obviously gives you a good amount of burst (Reckoning + Gunblade + Ignite can often take away over half of an enemy hero's health in one go), but the Codex gives you more support and sustained damage (more AP and some CDR instead of up-front damage). If the extra support isn't needed, then I find the Gunblade to be more useful, since it lets you kill people without having to stay in the fray.

Once you have the Gunblade and Codex, get yourself a Stinger and get started on building your Lich Bane (Sheen first then Blasting Wand). Finishing Nashor's Tooth isn't worth it yet since it's a pretty small upgrade over Stinger and Fiendish Codex - save that for after you finish the Lich Bane.

If the game goes on long enough for you to build all 4 items I listed, a few different items can be nice 5-6 finishers. Rylai's Scepter is a great item to have since it applies a (reduced) slow to your RF splash damage and gives you some health and AP, Abyssal Scepter gives a nice boost to your AP and MR and its passive works well with your RF splash damage, and any item that increases your attack speed (Madred's and Phantom Dancer are my favorites) can make your RF brutal in team fights, since at rank 5 it deals 40% of your normal attack plus the magic bonus to anything it hits, so high attack speeds on Kayle can give her a devastating late game. Really, it's up to you, but I try to make my Righteous Fury as deadly as possible with my 5-6 items in long games, since the game will go as the team fights go at that point.