Really don't know which one I should take. I want it to be pretty silent, practical, and I want it to have a good airflow (which is not the case for my sonata II and which is why I'm replacing it).
Well, I can't say much about the Silverstone, but the Thermaltake Armor Jr is pretty similar to my case, the Tsunami Dream. I've had nothing bad to say about my case, and I get very good airflow inside. I even manage to passively cool my PD820 with a small overclock.
One thing I would suggest is to not get the version that comes with the PSU. Select your own PSU, as the bundled ones aren't always what you're looking for.
A consideration that is actually very important is the number, type and physical location of "front-mounted" USB etc ports. Especially in the context of where your case will be placed in its normal working environment.
For instance, if you put your case on the floor under your desk, you want these ports on the front of the case, at least midway up the body of the case and un-obstructed so you don't have to get on the floor to insert cabels, jump-drives, etc. This is less of an issue if you decide to keep the case on your desktop, but why tie up space you could use for the monitor?
I think the location of the front mounted ports on the Silverstone case is bad. They are at the bottom and on the side of the case. This will mean that you have to get on the floor to insert cables, and the side facing location will require more space: not just to allow clearance for cable ends, but the extra clearance you will need for the physical length of USB Jumpdrives, but to actually insert and remove any devices, including space for your hand(s) to fumble around in, as you can't see the port(s) properly. The Thermaltake case does it much better.
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