I have a KEF KC62 sub and it maybe excellent. I do not have too much experience with subs to compare. In a few hours I will getting delivery of the $200 KEF wireless transmitter for the sub. It is supposed to be excellent and it will allow me to only have the single PC going into the sub.
The KC62 is small and comes in white and can be placed in a bookshelf (or other locations). I used it on a bookshelf prior to my current room. I plan on trying the sub next on a 28 inch tall stool from HomeDepot. The new KEF KC60 speakers (Baby Blades) gave me the idea of trying this with my KEF LS50 bookshelf speakers. The sub is so small that you have so many placement options.