David, you can use any driver you like in a "sonosub" design... you just have to cut the sonotube's length to fit the parameters of the driver you choose.
Members here tend to go with Shivas, Tempests, SVS and such due to the fact that these drivers deliver high quality sound for a reasonable price.
Some drivers are not suited for downfiring operation. Make sure the driver you choose is if you are planning a typical downfiring sonotube design.
If you lay the tube on it's side though, any driver can be used. Like Dave said its just a matter of optimizing the enclosure for the driver you choose.
However, there are drivers that represent very poor values, and some that represent excellent values like any other speaker.
My experiences with subs has been limited to car audio. I just remember how pleased I was with JL's. I've searched this board on sonotube threads and have learned a lot. I noticed the downfiring issue in the threads. I'll probably go with the Shiva. I like the sonosube at this site: http://www.extremezone.com/~stpeters/subwoof.html
Right now I have a Polk PSW450. It shakes the cabinents but I want ~20hz range, I want to feel it more. Thanks for the advice so far.
Any woofers will work in a sonosub design. The same theories apply despite the driver, unlike a T-Line which needs the right driver. I ran a 15w3 in a 5cu. ft. ported box with a 250 watts plate amp in my house. I built it for my friend's car, the thing shook the house violently at the right frequencies. But the woofers are way too inefficient for practical use in a house.