I would say monitor audio radius series, though on the expensive side compared to other small 5.1 HT speakers. Another would be the Mordaunt Short Premier series, about 25K for the set or the more expensive genie series.
Haven't heard the genie though it got good reviews. Heard the Monitor Audio Radius series, they sound big for their size. Of course when you compare it with floorstander on music, manipis. But on HT, cant tell the difference.