I recommend the nac, the swc, or the exact one bilbo recommended.
And Rick, although you are correct about the vendors saying things are good just for the sale, which slot of places and lfs do and kind of annoying because you don't know who to trust. But im sure you know too if you done business with him,but russ is not like that. Ill always take russ word. He has plenty of other skimmers for sale, some more expensive too, but for a 90 gallon, that's the ONLY skimmer he recommended to me. He is a very honest guy. I go to his place all the time, and he will tell me flat out if it's crap or not. And if he says I'll guarantee you will be more then satisfied.. Then I guarantee...I was.
For example, those new current USA lunar led strips. Russ showed me these. They look pathetic compared to the stunner strips. It's 4 very small square LEDs on a foot long strip. He told me about them twice, and I did not buy them because i did not think they would look that nice. I finally purchased one. Let me tell you, i went back and bought another...and then went back and bought one more. They were the very best led strips I've ever owned. He was right, and i should have listened to him in the first place...he just knows better. Thats why most people will take his word when it comes to a product...
From what ive read, the big difference ive noticed between the bubble Magnus nacs and the swc are...well...nothing. the run exactly the same and both amazing buys. But the difference I noticed with reef octopus super skimmer series and the other two, swc and nacs, is that the nacs and swc pull out a thicker skin mate, but the reef octopus super skimmer pulls out much much quicker. Not AS thick, but still disgusting. I personally have a nac 7. I have it connected to a 2 gallon container. To fill the two gallons of skin mate would take 2 or 3 weeks. A reef octopus would do it in about 1-2 weeks. Granted it all depends on bio load, but still, it's personal preference. Do you want it to be a thicker skin mate, or a quicker, yet a little more watered down skin mate? Thats your choice. But you have made the right choice so far and wait and save some more money. Anyone will tell you NOT to cheap out on your skimmer. Save the money and get your price range up to 250-350 and you options will be much better and much more efficient.