Personally I can't live without evolved Q. The additional damage and range are insane.

I've been going without the W evolution. Lots of people are saying R is the worst. but I dunno.

EDIT:

A build I like:

1. Start with prosp/boots/pots
2. Get Ionian boots, brutalizer
3. Then a vamp scepter and last whisper in whatever order. You can avoid the LW for a while if they aren't building armor, but eventually they will and it's an item you need at some point.

After this, it's all situational building.

4. You need a defensive item or two at this point. For AP heavy teams I like a combination of QSS and Maw. Against AD heavy teams I'll get a chain vest and finish my senguine blade, then finish Frozen Heart. I don't consider Frozen Heart core yet, since most of the time someone else has it and Kha'zix benefits more from AD than any other stat. If you went the AP route, finish up Senguine Blade after.
5. At any time, you can finish your Ghostblade for chasing power.

More like Rengar 2.0

Counter Khaz: Lightbringer.

Sort of. It's true that it completely nullifies his ult, but his ult isn't really what makes him strong anyway.

I have just felt too squishy going all AD.

Last night I tried a build:

Prospectors Blade/Boots
Phage
CDR Boots
Sheen
Vamp Scepter
Trinity
Zekes
Hexdrinker>Maw

Next I was going to go for an Atma's and then probably a LW(would have gotten that earlier if more armor was on the field of course).

He still did ridiculous burst and was a lot less squishy.

I personally evolve as follows:

E: The longer jump and extra mobility is just too useful.
Q: Dat burst
R: Juking potential more burst with passive procs.

The slow and larger AoE is nice and might be a priority if my opponents were more kitey. In that case I would probably give up Q. As he's plenty bursty without it, and the extra damage is just not as good as all of the utility options of the other Evo's.

evolve R and get 3x 40% dr ... still works even if your seen

panwar I just tried your build and I really don't like it.

I was tankier for sure but couldn't reallyd eal any damage until very late game.

No Brutalizer and no LW

haha what the hell

opens up options for Triforce or gunblade .. or even both

im kinda fooling around with a gunblade armor pen build my self , seems to do ok you get some nice sustain from gunblade wich commes in handy if your bot. or like me all over the map and regaining hp off minions inbetween fights ( that Q heal)

key items for me are mobility boots , gunblade , brutaliser AND ghostblade
build order , mobility boots -> brutaliser-> bilgewater Cutlass->ghostblade-->brutaliser-> gunblade

imo you dont need to be to tanky if you can jump in explode someone and jump out again or flee using ult i use armor and mr per lvl runes o beef him up a bid over time and filled the rest in with arp runes to increase phy damage and use the pretty much standard 9-21-0 mastery's for a phy damage bruiser derp

( U mad armor stackers ? )

Haha S'okay I've been building all AD/Arpen since I posted that and just trying to be smarter, and I think I might agree with everyone that it is the better build.