For our UK people
The Wharfedale Diamond Sw150 as mentioned in another topic. Especially the walnut version for its premium appearance.
Many positive pro reviews and user experiences and high ratings around the net. Miles away from any other affordable sub. Tried to get one from within the EU and was even willing to pay a bit more, but it is mission impossible. Hope they will release it as a succeeder to another sub in the EU range.
150 pounds / 170 euros is a great price. For what it is and its quality there is simply no competition at this price level as most ones have dealbreakers for appearing like toys, not going deep in frequencies, not having a crossover knob or literally quit working.(For example: Had a look at the reviews of an Edifier sub that did everything right but switched itself off at lower volumes due to an automatic sensor)
I expect that this might so far be the only sub "in its price range(!)" that remains desirable on the future 2nd hand market or could perhaps legitmately raise in trading price over time.