Not enough information to suggest "best". What type of "speeds" were you going to run the hosts at? How busy do you expect them to be? What special features, if any, are important to you? What speed and kind of fiber unlinks?

For instance, your edge might be, at one extreme, L2 switches like the Catalyst Express 5x0 series or Catalyst 29x0 series connected to Cisco Catalyst 3750G-12S acting as a collasped core, or on the other extreme, Catalyst 65xx-E switches with Sup32 or Sup32-PISA connected to a Catalyst 65xx-E Switch with Sup720 collasped core which also contains service modules. Lots of inbetween choices too.

For 320 hosts, physically you could run all on just one large switch stack or chassis, so except for physical topology requirements, unlikely you'll need more than a 2 layer (access and collasped core) model.