Im setting up a 75G cube and am trying to decide between a SWC 160 and Reef Octopus needlewheel 6. Which one is better in terms of efficacy, noise, longterm wear? First hand experience with one or both would be much appreciated.
According to this article the performance of the Octopus NWB 150 (needlewheel 6) is abysmal. This article is a few years old, and octopus may have improved since then, but I know the pump is the same, and the body looks to be roughly the same too, so I'm not sure how much it could have improved. As far as the SWC 160 I have heard that it is a great skimmer, but again, no first hand experience.
I personally use a Reef Octopus Extreme XS 160 on my 75g, but that retails for for $100 more than the NWB, so that may be out of your budget. If you can fit it in the budget it performs very well, but it's pretty loud. Some other skimmers in the price range you were looking at that may be worth consideration would be: Bubble Magus (curve 5 or NAC7 roughly $200) or the SCA-302 (eBay Bubble Magus clone skimmer, $135).
But again, depending on budget I would recommend not to skimp on a skimmer if you can. A few extra dollars now may save you from having to shell out a few hundred more down the line because you aren't satisfied with the performance. if you buy a quality skimmer like a Reef Dynamics, Vertex, JNS, Sea Side Aquatics, or Super Reef Octopus you will not regret the extra $100-$200 for the performance you get.
All good skimmer and any one of them will perform well for you. You should look at the SCA 302 skimmer as a strong contender with the other skimmers mention with the exception of the Diablo, which is a beast.