That depends on how you want to run HA. If you are only going to run Home Assistant Container or Home Assistant Core, Ubuntu is fine. Both of these methods will not give you Supervisor and the added benefits that come with it.
If you want the Supervisor and are planning to run on the Dell machine you mentioned, you have 2 options. Home Assistant Supervised or Home Assistant OS running in a VM using some like Proxmox.
See this post for an explanation of what each method gives you.