HYBRID BUILD:
Rune Build: Glyphs would be more efficient with AP per level.
Quintessences would be more efficient with magic penetration ONLY.
It should be said that Flat health quintessences are effective on ALL builds.

Item Build: Rylai's should be build earlier, Hextech gunblade should be build LAST, Nashor's tooth would fit very well into the build, build either after guinsoo's, or after zhonya's. if you want, a Madred's Bloodrazor could fit in there aswell. And, Don't get boots first, get Doran's Shield(preferably), its much safer, especially if you intent to B when you can afford an entire item.

Skill Build: Electrical Surge would be the best to max first, as the key thing about hybrid builds are their Attack Speed, and their On hit attacks( SUCH as Eletrical surge).

Mastery Tree: Again, Why sunder over Tenacity?

AP BUILD:
Runes: Check the link from DPS build, Seals would be more efficient with Dodge or Health/health per level. Glyphs would be more efficient with AP per level.

Item build: Haunting guise is a good item compared to its price, but if you get both Haunting guise, Sorcerer's Shoes, and 14,22 Magic penetration in runes, then the voidstaff is gonna be inefficient. Let's take an example of a target with 100 Magic resist, youll reduce it by 54,22(= 45,78), then reduce it with %wise reduction( Spell penetrate + voidstaff will = 49%, not 55%). 45,78*0,51=23,3478. This means the more flat magic penetration you get, the less cost efficient will voidstaff become, in this scenario, with that much magic penetration, an Abyssal Scepter( 70 AP, 57Magic resist, aura reducing enemy champs Magic resist by 20), be more effective!
If you decide you prefer voidstaff, then get mejai's instead of haunting guise, you are gonna have at least a few stacks, and it is even cheaper.

Skill Build: For AP Kennen, the most effective skill is Thundering Shuriken, followed by electrical surge, so you might consider to max Shuriken, then Surge. Your current build doesn't max anything "first" in that manner.

Mastery Tree: WHY Sunder on AP build? you dont NEED Armor pen on Caster builds, and neither does it outweight Tenacity(21 in defense), reducing all damage by 4%!

I'm gonna go through all the things I think needs a change here. taking them 1 build at a time. I'm gonna split them up in 1 comment each.

DPS BUILD:
Runes: For a DPS build(DPS as in you use Physical damage and auto attacks to deal damage), does NOT use Magic penetration(except for madred's bloodrazor), nor Ability Power.
Also, you're not using efficient runes, I'd like to forward you to this "build" explaining how to use efficient rune builds: http://www.mobafire.com/league-of-legends/build/rune-tips-what-secondary-and-primary-means-and-more-24255
To make your build efficient, you could 1. change your seals to either Lucidity(Energy regen per level), Vitality( Health per level), or Evasion(Flat Dodge).
2. Change your glyphs to either Force(AP per level), Shielding(Magic resist per level), or warding(Flat Magic resist). Also, make sure your only using 1 type of each rune(as in 1 Type of marks, 1 of seal, 1 of glyph and 1 of quintessence) as this will make them more efficient(ish) too.

Im just gonna ask, why are you getting both Armor Pen and Magic Pen?

Item Build:
Doran's blade: I'm not saying this is a bad choice, but Doran's Shield is a better choice for pretty much all champions that would pick Doran's Blade.
Berserker's greaves: If you wanted Magic penetration for your Madred's you could've gone with Sorcerer's Shoes and gotten much more out of your boots.

Skill Build: For DPS Kennen, the most useful skill is electrical surge, as every 5th attack will deal 40/50/60/70/80% more damage. Which means you might consider maxing it first!

Mastery Tree: Lethality Increases Critical strike DAMAGE, which means with your poor 0,66 Crit chance thats not gonna happen. To be more specific, its on average gonna take you 151 hits per time you will crit.