If you want something different than what you have, I'd recommend upgrading away from cones. Waste of footprint space. Also, knowing how much footprint space you have would help...if you only allow a tiny chamber for your skimmer you'll be limited to these pump-inside designs. Very compact and clever, but not the best design. Your tank will do the best if you design your sump with the skimmer in mind. Footprint issues are usually not a problem.
The NAC9
appears to be a $400 skimmer with an air intake of about 1000 liters/hour. (Their gallon-rating would (
IMO) apply to systems with low stocking levels and few, to no SPS corals.) I think their
NAC66, at $329 with free shipping would get you a lot more bang for your buck due to the larger body (I'm guessing* about 2.6 gallons), if you want to stick with this brand. Since you're familiar with this line, we'll compare other makes on the air-capacity first to make comparing apples to oranges a little better.
A Reef Dynamics that would be on the same performance level as the NAC9 would be their
INS-250. $500, but much larger capacity with a 3.7 gallon body. When cost is not of the utmost concern, these guys are my favorite. Easy to use, easy to maintain, high quality design and build, easy to contact, one-man factory here in the USA - so even something custom is a good option to consider with them. Get a sump+skimmer system (would be custom for your size) from them for ideal performance. If you tend to buy "built like a tank" reliability, get the skimmer upgraded to Eheim pumps. Not cheap.
However, if dollar signs win the day, then any
H&S or
Reef Dynamics knock-off like ASM or some of the Reef Octopus lines would be fine as well. Like this
Vertex IN-250 at $320 for about 1000 liters/hour and a (guessing* again) 2.6 gallon body. Or this
DDNW-250 for $600 - a steal which should pull about 2400 liters/hour. (Personally, this is the performance level I'd be looking at for a tank of the size you're talking.)
If you wanted to look at something different, I'd even suggest considering an AquaC EV series. These skimmers frustrate some users by (in my estimatation) being too flexible and therefore seemingly difficult to "dial in". Don't let those folks dissuade you - install it correctly and have patience. It's a great skimmer design, but not necessarily for everyone. Depending on the space issue again, I'd suggest acquiring a used
EV400, or if space turns out to be an issue I think the
EV240 would even get you by if you push it with a bigger pump. Depending on your sensitivity to power usage**, you may have to spend up on a more efficient pump - most people you'd be buying from (used or new) outfit these skimmers with Mag or outboard pumps that are universally not very efficient. Something like an Ocean Runner
6500 (1700gph @ 95 watts - your best buy), Water Blaster
HY7000 (1700gph @ 88 watts) or even an equivalent Red Dragon, but there's nothing "good value" about that one at around $600.

You could even choose to pick something in the neighborhood of 2400gph - Tunze's new
Silence Pro has the be the go-to at
$380 for its performance and features, but you'll be throttling the pump back some (which will make it use less power) at that level of flow. Everything said here more or less applies to the AETech's
ETSS Skimmers. Similar performance, flexibility and ability to frustrate some users.

Consider their Sump Buddy 60 or the
700 (my favorite - run with a Quiet One 3000, Ocean Runner 3500, Eheim 1260 or 1262, etc - a lot less pump) or 800 models at the bottom. Nice feature is these all have upgradable necks, so adding an even bigger pump is very possible.
Another option I still like for smaller spaces is the
Tunze 9021. At 1300 liters/hour it's a performance upgrade, but not the highest value at $500+. This one will also perform best on an in-tank installation.
Lots of good options out there. Bubble plates and cones are gimmicks just like colored plastics though - so my recommendation is to at least not pay extra for them, or even better avoid them. Lots of good options out there.
Good luck!
-Matt
* (pi*r^2)*h)/231 = gallons in a cylinder....taking the body diameter and the skimmer height as they are given, and then estimating the height of the body is how I'm figuring.
** There's another side to the wattage in pumps...the "waste" is just given off as heat. If your tank isn't needing to be cooled, then a high wattage submersible pump is not a problem. As long as it's a quality pump and doesn't break down, you have nothing to worry about. The "saved wattage" from switching to a higher efficiency pump would be given up just the same to a heater to keep the tank at the correct temperature. This is especially likely if you have a well ventilated canopy with a T5HO or MH fixture or run LED lighting.
OTOH, if you're kicking it old school and are adding tons of heat via the lighting system (this includes most people with factory canopies, people with built in tanks, and me), then you may well benefit from spending extra on a super-efficient pump (and an
upgrade to LED's). The "extra cost" might save you from having to spend
real big bucks to purchase and operate a chiller.