My advice: don't pay much attention to league tables - they are nearly always wrong. I wouldn't call Newcastle, Leeds or Sussex particularly prestigious. If you're not willing to consider London or Scotland, then after Oxbridge I think the top 3 are Durham, Warwick and Manchester. But you should also consider Bristol, Birmingham, Southampton, Nottingham, Exeter, York and maybe also Royal Holloway (which isn't actually in London, despite its name).