For my own projects I buy whatever Supermirco platform the data center manager has a volume discount for or I find used Dell equipment from third party sellers or ebay.

At work we rent by the month based on needs and availability. I never know the brand, just the specs. Lately AMD based servers have been more competitive.

I rarely run more than one VM at home at a time. Hosting multiple VMs what the big iron is for.

At home 32 to 64GiB is plenty. For the data center I generally order 384GiB now. It varies depending on use case.