I started with a DIY HOB skimmer that came with the used set up I purchased. It was an old school, wooden air diffuser, counter current unit, run by a small air pump & a small powerhead. Worked fine, very quiet. If quiet is what you're looking for, don't pooh pooh this old school technology, it does the job.
A year or so later, I purchased a second used tank from a local who was shutting his down. It came with a Remora C HOB skimmer. Supposed to be so much better than old school I had, so decided to give it a go. It turned out to be the noisiest thing in the house & the skimmate it produced was only ever a thin tea. My wooden air diffuser unit produced bona fide sludge, was quiet & used about half the electricity as the Remora. I finally cracked the intake on the Remora one day during cleaning & was happy to go back to the wooden technology!
I did a few modifications to the old skimmer, including a ball valve & slip union on the return line for improved control of water level & an air diffuser manifold so I could run two air diffusers. I've also built my own monster size wooden air diffusers out of basswood, but the last few ended up leaking due to my poor workmanship, so I'm back to store bought diffusers. I use a much larger air pump now as well & I think this helps the air diffusers last longer. I can get 6 months or better out of the diffusers, so that's not bad.
In the end, what makes a skimmer most efficient is smallest bubbles possible & maximum contact time between the bubbles & the water they are diffused into. Much of the newer technology with cones, diffuser plates etc. may help somewhat, but generally the improvement is negligible over old tech, especially when you consider what they charge for some of these things. I've seen few methods that create finer bubbles than a wooden air diffuser and with a long tube & small power head to circulate the water slowly to maximize contact time, the results are more than adequate.
Downside I guess, is you have to build it, unless you can find a used one somewhere. Mine is starting to have salt creep issues at some of the joints, so I'm going to have to start thinking about either repairing it, or building a new one from scratch... bigger, arrrr