Following the merger with Broadcom, VMware ESXi has reached the end of its general availability, resulting in the discontinuation of security updates and licensing; it is no longer possible to get a license for ESXi, even the free evaluation license is being discontinued, while it may be technically feasible to install ESXi if you have an ISO available locally when it can no longer call home your installation may become limited.
Proxmox provides community and commercial support and has a wealth of documentation for management.
Links:
VMWare ESXi end of life
Proxmox
Proxmox community support
Proxmox documentation