Look in bike mags for results of the new "sharp" test. it's a standard test of the helmets safety. the results are surprising, some £400 helmets score less than some £100 ones! Let it guide you but you need to try them on. iN the city i'd be tempted by a flip front one.

Ive recently bought an HJC carbon from Hein Gericke for £199 and im very pleased with it. Ive been a top of the range Shoei man for years and was a little dubious about buying something cheaper but have to say im pleased with it.

Being made of carbon fibre it is lighter than most other helmets and has a built in flip down sun visor.

The best quality helmets which don't cost the earth are HJCs, the designer of these South Korean lids is the ex-chief designer of Shoei. They really are top quality lids at almost budget prices.

You need to think about what you need from your helmet.

I would recommend a helmet with a built in second tinted visor which can be flipped down. It saves having to carry a second visor and the BiB don't have an issue with these.
I would also go with a double D lock rather than the seatbelt type clip but that's my preference.

You need to go and try some helmets on as what fits one person does not fit another. I don't have a Shoei shaped head but an Arai fits perfectly.