SBs are not bad, but tend to be on not great value - ie expensive for what they are.
I will tell you this - most of our regulars, including me are on other side of the atlantic ocean and for example Tannoy is relatively rare visitor in these parts.
From your selection I'd suggest you chose between MA S6 or the Tannoy.
Other brands worth looking at are British Wharfedale, Swedish XTZ and for sub again from UK BKElec
http://www.bkelec.com/
I haven't heard bad things about KEF Q or R series, but never heard them in person.
What you have today is tiny speaker 5.1 system - which if you want to seriously update - you'd need new Fronts including matching center and a new sub. that tiny one is won't keep up with larger speakers.
You should match speakers to room they are in - smaller rooms would be ok with bookshelf speakers, but larger room will gain greatly from tower speakers.