Yeah I quite like the layout in the Aquila, it's a little like the Dead Silence, but Xigmatek do seem a bit shoddy at availability/info.
If I was going for a mATX build, I'd probably just bite the bullet and stick with a conventional tower. In that instance, the difference between ATX and mATX is so small, ATX is a very viable option, even if you are trying to keep the size down. The Corsair 350D for example, is a very popular high end mATX choice, but due to it's 5 expansion slots (to allow for SLI/Xfire more comfortably) and excellent radiator support, it's not an awful lot smaller than say a Fractal Design Arc Midi or Core 3000, which you can fit an ATX motherboard (as well as basically anything else you want).
Starting at ATX, you can do similar AMD builds at this form, but as I'm about to go smaller I'm keeping it simple. You can spend more or less in various areas, but this is vaguely sensible. Yeah it's a bit over on funds, but that's due to prices bouncing around a bit, normally I'd have gone for the Arc Midi over the Core 3000, but then it'd have been quite a bit over. On another day it could be comfortably below 1k, the prices on 280X graphics cards shot up and it kinda took the GTX770 with it as availability ran low.
The main "weird" pick is the Z87 motherboard with a non overclockable processor. The reason is that you mentioned thinking mATX might be the way to go over ITX. As the main difference between the two is support for an additional graphics card, I thought it was something you might want to allow provision for. Ditching the SSD gives you plenty of funds to buy an overclockable k-series processor and a CPU cooler, if you want to exploit the full value of Z87. If SLI is totally not of interest, then you can drop to a H87/B85 board in both of the next two builds, though at that point ITX starts to make a lot more sense.
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks
CPU: Intel Core i5-4440 3.1GHz Quad-Core Processor ($179.99 @ TigerDirect)
Motherboard: ASRock Z87 Extreme4 ATX LGA1150 Motherboard ($134.99 @ Newegg)
Memory: Team Vulcan 8GB (2 x 4GB) DDR3-1600 Memory ($72.98 @ OutletPC)
Storage: Samsung 840 EVO 120GB 2.5" Solid State Disk ($88.99 @ Amazon)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($59.98 @ OutletPC)
Video Card: Gigabyte GeForce GTX 770 2GB Video Card ($329.99 @ Newegg)
Case: Fractal Design Core 3000 USB 3.0 (Black) ATX Mid Tower Case ($74.99 @ NCIX US)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($49.99 @ NCIX US)
Optical Drive: Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer ($16.98 @ OutletPC)
Total: $1008.88
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-01-13 13:04 EST-0500)
Transferring that down to mATX is really simple. Change the motherboard to the "M" version and change the case. Same comments apply really. I've stuck in the Aerocool as it's probably the closest thing to the Aquila. You can do 2-way SLI in this if you want, but you won't be able to install a Wifi card for example if you do so.
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks
CPU: Intel Core i5-4440 3.1GHz Quad-Core Processor ($179.99 @ TigerDirect)
Motherboard: ASRock Z87M Extreme4 Micro ATX LGA1150 Motherboard ($122.99 @ Newegg)
Memory: Team Vulcan 8GB (2 x 4GB) DDR3-1600 Memory ($72.98 @ OutletPC)
Storage: Samsung 840 EVO 120GB 2.5" Solid State Disk ($88.99 @ Amazon)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($59.98 @ OutletPC)
Video Card: Gigabyte GeForce GTX 770 2GB Video Card ($329.99 @ Newegg)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($49.99 @ NCIX US)
Optical Drive: Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer ($16.98 @ OutletPC)
Other: Aerocool DS ($120.00)
Total: $1041.89
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-01-13 12:58 EST-0500)
Dropping down to Prodigy size (actually still pretty large). I've had to change the PSU for a smaller one, so I went with a wired one, there's a lot of space for tucking cables in the Prodigy so it's not a massive issue.
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks
CPU: Intel Core i5-4440 3.1GHz Quad-Core Processor ($179.99 @ TigerDirect)
Motherboard: Gigabyte GA-H87N-WIFI Mini ITX LGA1150 Motherboard ($107.99 @ Amazon)
Memory: Team Vulcan 8GB (2 x 4GB) DDR3-1600 Memory ($72.98 @ OutletPC)
Storage: Samsung 840 EVO 120GB 2.5" Solid State Disk ($88.99 @ Amazon)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($59.98 @ OutletPC)
Video Card: Gigabyte GeForce GTX 770 2GB Video Card ($329.99 @ Newegg)
Case: BitFenix Prodigy (Orange) Mini ITX Tower Case ($74.75 @ OutletPC)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($49.99 @ NCIX US)
Optical Drive: Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer ($16.98 @ OutletPC)
Total: $981.64
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-01-13 12:57 EST-0500)
Down to "proper" ITX scale, you have the Elite130. Not the most pretty case, but really compact, still capable of fitting most full sized components though.
PCPartPicker part list /
Price breakdown by merchant /
Benchmarks
CPU: Intel Core i5-4440 3.1GHz Quad-Core Processor ($179.99 @ TigerDirect)
Motherboard: Gigabyte GA-H87N-WIFI Mini ITX LGA1150 Motherboard ($107.99 @ Amazon)
Memory: Team Vulcan 8GB (2 x 4GB) DDR3-1600 Memory ($72.98 @ OutletPC)
Storage: Samsung 840 EVO 120GB 2.5" Solid State Disk ($88.99 @ Amazon)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($59.98 @ OutletPC)
Video Card: Gigabyte GeForce GTX 770 2GB Video Card ($329.99 @ Newegg)
Case: Cooler Master Elite 130 Mini ITX Tower Case ($49.99 @ Mwave)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($49.99 @ NCIX US)
Optical Drive: Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer ($16.98 @ OutletPC)
Total: $956.88
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-01-13 12:55 EST-0500)
I've tried to keep some consistency across the components, but there's a lot of choices within motherboards and PSUs for example. I stuck in an SSD too, it's a bit of a luxury but the main alternative is spending an extra ~$100 on graphics and at 1080P it's really not worth it.