5 - Dell R610 with 96GB Memory in Each - Also has a 2 Port Intel 1000 Card (6 Nics Total)
What are you doing with 5 R610s that can't be done with two R720s? The memory count implies that the workload per node could be consolidated further.
The advantage 5 Means for N+1 one you only need to reserve 20% of resources in reserve. (now I'd argue 3 hosts is a GREAT cost sweat spot, as you only need 33% resources in reserve and you don't have to license 5 hosts which falls outside of the SMB kits for Hyper-V System Center, and VMware Essentials/Essentials Plus).
96GB of RAM is kind of a joke these days. You'll get more bang for your buck going 192GB on 3 hosts. (Unless you have done a DPACK/MAP report that shows crazy high CPU usage compared to normal use cases...).