We currently have a n7k and are looking to expand our datacenter network. I have thought of getting a pair of 5672 for our vmware cluster but the Cisco enginner was suggesting the n9300. But not sure if that is the direction we need to go. When it is said and done we will have 3 sites and we do have layer 1 connectivity to all 3 sites. We do want to run a converged network, ischia and general server traffic. Any thoughts?
Your Cisco engineer will recommend the N9K over the N5K 9 times out of 10 (in my estimation) for two primary reasons. First because the N9K is typically less expensive and second because it positions your network for ACI. In your case, the N9K also works well with the N7K because you can configure VXLAN (overlay technology, also native in ACI) not only between your sites but down to the N9Ks, thereby maintaining your layer 2 for the VMWare cluster. The only drawback for the N9K is that it is Ethernet only so no unified ports.
Of course without knowing your network I would be hard-pressed to offer any substantial advise, but based on what you provided I'd say there's a pretty good chance your Cisco engineer has these reasons in mind.
If you don't have SAN (FC/FCoE) network on the same switches with LAN (N7000/N7700/N6000/N5000) and you don't plan to use SAN (FC) in future, Nexus 9300 will be better choise.
1. ACI ready - maybe you will migrate from NX-OS to ACI network in future (then you must only change operating mode, currently there are bundles with both - NX-OS and ACI - licenses in price of one of them)
2. Network Tapping - flexible traffic redirection with Nexus Data Broker to additional analysis
3. Telemetry - Nexus 9300-EX have support for Cisco Tetration Analytics (quite expensive as for me), so you can precisely monitor your DC
4. FCoE support - FCoE NPV support - on roadmap!, but it was announced
5. Price - it should be lower than Nexus 5600 series, there are many discount bundles