How about Nepton 220 or 240?
Two thoughts about that. First, there are certainly comprehensive comparison reviews that provide insight of a rank-order between the Neptons, other AiO's, and the heatpipe coolers.
Second, you have to convince yourself that the review isn't hyping a cooler by omitting competition you know is stronger. Generally, the larger number of coolers in the database of comparison, the more likely the review is reliable.
You can question the testing methodology, and sometimes testers have to depart from a standard approach: for instance, with coolers that don't come with fans, they choose a mainstream fan and use it for the tests.
Let's see what we can find right away on these Nepton models:
http://lanoc.org/review/cooling/6986-cooler-master-nepton-240m?showall=&start=4
http://www.ocaholic.co.uk/modules/smartsection/item.php?page=5&itemid=1480
http://www.kitguru.net/components/henry-butt/cooler-master-nepton-240m-liquid-cpu-cooler-review/6/
None of these have the comprehensive comparison more common with Frosty Tech's reviews; the comparison involves a handful of liquid and air coolers. The first two reviews don't seem to do much to get a testbed with an overclocked profile. Even so, the limited comparison list can be compared with more comprehensive reviews in which some of the coolers appear, and you can infer a more thorough rank-order.
The last review gives us something we like to see: a good 4.7 Ghz overclocked test-bed using a Sandy Bridge E processor. You can see that the Nepton 240 performs better in those tests than the NH-D14 by about 5C degrees. And it is likely the thermal wattage of the overclocked testbed is much higher than 140W.
What am I going to say about that? I can make up all or a decent part of the 5C difference by ducting and a high-CFM fan on the D14. But even without the ducting and powerful fan, it seems to me that the EVGA ACX cooler is in a dead heat (ha! -- a pun) with the Nepton. "Oh!" you say, "the ACX isn't in the review." No, but it was compared to the D14 in a Hardware Secrets review that I've verified and confirmed here on this thread. It is simple logical inference. And if you add the ducting, you get better than Nepton performance.
On the other hand, add more powerful fans with rubber isolators to the Nepton. Other more minor things can be done to it. The biggest challenge with a dual-fan AiO would seem to be whether you can get any performance at all from ducting it. You can double the fans for push pull; you can get more powerful fans like an AP-30 or Noctua iPPC 3,000 RPM; you can use rubber mounts on those fans; you can wrap the fans in Spire rubber.
but it just shows how close the AiO's and heatpipes perform together -- especially if you're willing to do more than the average consumer does with a new appliance. That takes me back to my earlier remarks: these new processors are going to show higher temperatures at the same thermal wattage with the same coolers as opposed to SB processors -- because of the die-shrink. If you aren't comfortable with load temperatures in the '80s and '90s, you can "de-lid." Or something with greater cooling capacity is required.
And the fact still remains. If a single-pump AiO fails, there's no backup. If a fan on a heatpipe cooler fails, it will continue to function. Pumps have a MTBF of some few years or so; the MTBF for a heatpipe is 1 million years. This isn't to say you shouldn't buy AiO's. It's not to say you MUST use custom water cooling. It's just an appraisal of the situation, even with AiO's with good, reliable pumps.
Does that satisfy you?