i agree on the arai (a vector can be had for under $400), best fitting helmet i've ever tried on. the scorpion's not bad either though it's a tight squeeze on and off and doesn't have the plush interior of the arai--it's darn good for $200 cheaper. tried on the higher end bell the other day and it was pretty nice if a bit pricey.
check
webbike world's best of. . . a good place to start. they have
a ton of helmet reviews up on their site, too. i trust their reviews but keep in mind that the guy that does the reviews has a really round head (most folks are more oval-ish) so take his advice on fit with a grain of salt.
as for safety, they will all be safe, honestly. if you have some time to read a really interesting article that's posted around here before take a look at the link below
Motorcycle Helmet Performance: Blowing the Lid Off