Sub? Can't Decide

"not disturbe the neighbors".. any sub IS going to disturbe the neighbors unless it is turned off.
If you live in a condo with adjacent walls, or an apartment, the part which is the killer for complaints are low frequencies.
If you want peace with neighbors, skip the sub. In a 10' by 10' room it is just asking for trouble. First off you will hardly get any bass you can hear IN the room, yet WILL create a LOT of bass travelling THROUGH the walls into the rest of the building. It will suck.
Just my two cents as a lifetime apt dweller. ((our opinions and mielage may and will vary.))

One reason i love my Magnepan 3.6 is the LACK of bass going through walls. The bass meeting around the edge of the dipole cancels out pretty good at the wall boundary.
Yet manages to sound good at the seating position.
I love them. And I do not bother the other tenants.

I use to own a Hsu and thought it was a very good sub for the money. Don't know anything about the other two.

There is a Linn Akurate 221 8" sub on A'gon right now for $995. The retail on this is $3750. I have one in my living room and it is a fantastic sub for both music and movies. It's perfect for a moderate size room -- not big enough for a big room. If you turn the gain low enough, it will fill out your low end in a very subtle way without bugging the neighbors. If you want to spend less, there are some open-box specials on small REL subs on vanns dot com for good prices.