Morning,
I agree with rurffy and some of the other answers to provide it in summary:
Options:
1. Export vm as a OVF and import into new system - Pro's clean Con's slow as crap lots of downtime copy up and down
2. Shutdown VM and use SFTP between your esxi hosts to send it - Pro's clean con's slow as crap lots of downtime only one copy
3. Share storage between esxi nodes and storage vmotion to shared storage then power off and add to inventory in new vcenter - Pro's least downtime
4. Add one ESXi node in the destination location into the sources vcenter and use storage vmotion without shared datastores (must be running 5.1) - Pro's no downtime Con's fails a lot
5. Use vsphere replication to replicate the vm from the source to the destination with a 15 minute interval then shut down source for 15 mins ensure replication and power on in destination - Pro's - No manual intervention required Con's 15+ minutes of downtime per host plus need to install replication agents
I might be missing one or two additional possible options but which one you choose really depends on your requirements around downtime and your hardware available options. I do #3 a lot because most people are willing to endure a reboot of the vm.
Please let me know if you have any questions.
Thanks,
Joseph