MS-A2 has better specs, if spending this much money, I'd probably go with the newer device.
What do you need the device to do? Or I guess, how much performance do you need? For light duty you could go with an HP T740 or T755 with 64GB of ram and a decent low profile NIC and run either ESXi or XCP-ng. Not sure why you would want ESXi unless you deal with it at work. I would expect Proxmox to run fine as well, but not tested. Again, this is for light use to teach you what you might need to apply to a production system.
As you can see, I have a few HP T740. The top shelf has 3 XCP-ng in a pool, another XCP-ng, and a Debian "workstation". Next shelf down has 3 vSphere 8, and a Truenas. All save one of the T740 have dual 10gbps connections, and all have an a+e Intel i226v card installed where the wifi goes. The "workstation" currently has an Intel i350 quad port installed, it can be turned back into an OPNsense firewall when/if needed.
The old HP DL360 gen8 below are not currently in use, I wanted to reduce power draw with the mini PC.
Around the back are network switches, a Mikrotik CRS326-24s+2q+ and an old Cisco 2960s with POE+
I've since removed the plywood top and replaced with acrylic sheet to let more light in.
The keyboard tray will hopefully be replaced with an Uptyma keyboard/LCD device so I don't need to look up so high to see a monitor. Arrives today and the only thing I'm not sure about is if it comes with rack rails. Might be a quick bolt in change, might require me to look through the boxes of rails I have from work and modify something to fit.
