EF vs Heatkiller - Best WC Blocks?

What would you prefer, a Lamborghini, a Ferrari, a Bently, a Rolls Royce, an Aston Martin, a Corvette, etc.

Everyone will have their own opinion as to the best depends on taste and need.

You'd be better off listing your selection of items you've chosen and asking for comment, or at least the PC specs (make/model of parts) as it will narrow down the list of possibilities.

And checking the W/c sticky never hurts newcomers  
EK copper blocks are fine btw, just avoid their nickel blocks
Moto

I did the read sticky. Unfortunately the review sites mentioned don't have any proper heatkiller comparisons. They had the standard blocks like koolance or XSPC.

About the car comparison, all of those cars have a specific purpose. Ferrari is good for red light/green light, bentley for looks and comfort, and corvette for tracking. Ride in corvette ZR1 will be so stiff in city that you will want to kill yourself. But in a race track, it will run circles around a bentley. Reverse is true for bentley, you will be outlapped by a turbo charged honda civic in a race track.

For my purposes, I am looking for a) quite, b) efficient, c) performant WC loop. I'm willing to spend about $1,500 just for WC, so money is not an issue to some extent. This loop will most likely cool a Tri way GTX 680 SLI with 3960X cpu and 32 gb of RAM.

I am also quite puzzled about the GPU blocks for these 2 brands. Seems like heatkiller's GPU block is far superior than the EK, but then there is also aqua that excels in GPU, so I'm not sure. What I'd have preferred is to have my entire loop from one brand and EK is the only one that provides every part that I need.

See you have your opinion bout cars too  .

You've answered your own question; you'd prefer EK blocks. The current gen nickel blocks are ok, but the prior revisions had issues with corrosion. Some people will advise you to stay away from them due to galvanic corrosion eating away at the nickel, but then after going all copper blocks and rads (these are usually copper/brass) and throwing nickel plated barbs (most barbs are nickel) it seems pointless to stay away from the nickel blocks if you know they're decent blocks.

I haven't put my EK blocks in yet so can't comment on performance.

NO nickel EK blocks!

** but then after going all copper blocks and rads (these are usually copper/brass) and throwing nickel plated barbs (most barbs are nickel) it seems pointless to stay away from the nickel blocks if you know they're decent blocks**

I'm one of those who will steer you away from EK Nickel blocks, I am also one who has nickel fittings, just not EK Nickel  
Their solution for their plating problems was 'you are using the wrong coolant (distilled water, the best coolant out), you must use our approved coolant or lose your warranty'
I dislike that from a company so quite aside from the damage issue I can't let anyone buy EK Nickel, I bought two EK VGA HF copper Supremes for my gfx cards though cheerfully a few months ago,
I would say again Op, stick to copper blocks rather than having to compromise on other things to accommodate EK's Nickel peculiarities, in the end it is your choice but you did come here for advice and this is whats on offer  
for pumps you can't go wrong with a mcp655b or D5
Reservoirs are simple enough and unless you go down the FrozenQ line are pretty much all the same,
I wouldn't bother with mobo or ram blocks so don't let that restrict your choice of mobo, pick the mobo thats right for your build, tastes etc over whether or not theres a W/c block for it,
Moto

look up "Stren's 2012 CPU Water Block Roundup" rules of the site prevent me from linking it ill try to talk him in to posting them here. Gives a brake down of every major cpu water block.

http://www.extremerigs.net/
Heres his own sites posting, theres no issue with linking other sites Qun, unless its 'winanipad' kind of spam, which usually gets reported pretty fast  
Moto