VMware is not buggy. In IT we have to work around so many things for products to work the way we expect, or the way we want. I have not had to work around things with ESXi. It works as advertised.
Sever uptime. Even with hardware failures, and system bugs, VMware keeps our systems up. ESXi has been reliable. I never even think about the OS failing or having issues. That is one less thing to worry about.
Server deployment. We can deploy a new server in minutes. Some servers come preconfigured with OVF files where we just tell VMWare to set up a new server and point to the config file and tada there is a new server. We can create templates, where the OS and updates are already installed and we just create a new server from the template in minutes. I actually prefer creating one from scratch, and it only takes a few minutes to choose the hardware and start the OS installation. The longest part is installing the OS. It takes forever at my company to approve spending any money. With VMWare, I can set up new servers without any cost so there is no delay. When I want a server, I set it up. I don't have to wait over a month to design, get approval to order, wait for delivery, then set up the hardware, etc. It is fantastic, and such a time saver.
VMWare's Compatibility Guide on-line is excellent. It is very detailed and easy to discover if there will be any hardware issues. When adding or replacing hosts, this is a must-visit site. It has answered every question I've had without having to call support or talk to anyone to analyze if this hardware will match that one. It is a user-friendly site that gives you all the information you need. It has given me a starting point for buying new servers when my company changed its standard on server hardware. I would not have known where to start in configuring a new host, but this site told me what was compatible with what I had and it became an easy task.