Placing the subwoofer tightly in a corner will give maximum output from the subwoofer, but ONLY if both walls are clear of furniture etc. for at least 8 feet, which is not your case.
You will probably not want that location; a room diagram would help form an opinion on where to put it. Experimentation is usually needed to get the best performance. Downward-firing subs are easier to place properly.
Most rooms are large enough that it takes a 12-inch subwoofer with at least 300 watts of RMS power to generate enough clean undistorted bass. Most 8 and 10 inch subwoofers are not adequate, but if your room is very small, it might be an exception to the rule.
There are very few subwoofers that cost less than $300 that are adequate for most situations. Cheaper ones just generate thumps or puffing that sounds like an elephant farting.
If you are not prepared to spend that much, you may be better off getting front speakers with good bass and not using a subwoofer.
Originally Posted by malnutrian
I am not sure how to place my subwoofer, which I have decided to place within the rear corner of the room next to the sofa. The thing is, there's another cabinet right next to it, so it is indeed "surrounded" by sofa, wall and cabinet.
I have not actually bought it, but looking at a 8 inches one. Does it really matter if I choose the front v.s. floor ones? If the front ones, which direction should I face it??