I ran the free edition of ESXi on the homelab box for a couple of years and it was, mostly, fine. This month I wiped it and put Proxmox VE on instead, and I should have done it ages ago. This is the why, for anyone weighing the same swap.
The free ESXi licence is a slow accumulation of small irritations. No API access without a paid tier, so no clean automation. The web client kept changing its mind about whether it wanted Flash or HTML5. Backups meant a third-party tool or a manual dance. And the hardware compatibility list is fussy in a way that bites you precisely when you add the cheap NIC you found on eBay. None of these are fatal. All of them are friction, and friction in a homelab is what stops you tinkering.
What Proxmox actually gives you
The thing that sold me is that Proxmox runs both full KVM virtual machines and LXC containers from the same interface. That distinction matters more in a lab than I expected. A Linux service that doesn't need its own kernel, a DNS resolver, a reverse proxy, a small database, can run as an LXC container with a fraction of the memory and near-zero boot time. The things that genuinely need to be a whole machine, a Windows box, a kernel you want to break on purpose, stay as KVM VMs. One pane of glass, two tools, sensible defaults.
It's Debian underneath, which means when I want to do something the web UI doesn't cover, I drop to a shell and it's just Linux. No appliance lock-in, no shell that's been deliberately hobbled. Creating a container from the command line is the kind of thing I now do without thinking:
pct create 101 local:vztmpl/debian-8-standard_amd64.tar.gz \
--hostname dns01 \
--memory 256 \
--net0 name=eth0,bridge=vmbr0,ip=dhcp \
--storage local-lvm
256MB for a DNS resolver, up in a second or two. Try that with a full VM and you're wasting half a gig on a kernel and an init system you didn't need.
The honest caveats
It's not all upside. ESXi's bare-metal performance and its driver support for oddball enterprise hardware are genuinely good, and if your day job is VMware then running it at home keeps your skills sharp. Proxmox clustering and its HA story are capable but want at least three nodes and shared storage to be worth it, which is more box than most labs have. And ZFS, which Proxmox supports nicely, will happily eat all your RAM for cache if you let it, so size accordingly.
For a single-box lab where I want to spin things up, break them, and not think about a licence, Proxmox wins comfortably. The LXC-plus-KVM combination alone changed how I use the lab: I provision far more, far more casually, because a container costs me almost nothing. The migration took an afternoon, most of which was me reading rather than doing. No regrets.