Have spent most of last few days (obsessive me even choosing to avoid sleep!) researching a bigger model for us. One that seems to get rave reviews on the UK Campsite webpage (check any choices on there) is the Gelert CAdiz. \link{http://www.outdoorworld.org.uk/acatalog/copy_of_Gelert_Cadiz_4_2.html\here}
Not one for me (I prefer domes) but I am told it's good.
Also, the Jamet range \link{http://www.outdoormegastore.co.uk/acatalog/Outdoor_Megastore_Family_Dome_Range_28.html\ here} is said to be good, haven't found a complaint anywhere yet- but most of the sites about it are in French!! 
The Vango \link{http://uk.nextag.com/VANGO-Aspen-500--zz85637243zukzB3z2--COMPARE-PRICES-html\ here} looks good but I have heard complaints about pitching it, similarly the Colorado tents.
The chap at the sales place we went to recommended the \link{http://www.springfieldcamping.co.uk/brands/Vango/Diablo+600\here} Diablo- they do a 4 person. I'd trust him as they didn't actually stock it! He has used one for a while apparently.
Vango Aurora's are about fairly cheap atm, not enough living space for us but then there are 5 of us. \link{http://www.discovercamping.co.uk/Vango%20Aurora.htm\ here}
If you wouldn't mind a bit mroe space, the current hot favourite from the reviewws I have read is the Gelert Quebec. Not my cuppa tea (the shape) but here: \link{http://www.outdoorworld.org.uk/acatalog/copy_of_copy_of_copy_of_Gelert_Quebec_8_4.html\here}
And \link{http://www.discovercamping.co.uk/Gelert/Gelert-Tahoma-6.htm\ this} is what we decided on for us 