Servers and Workstations

What are requirements you see game developers looking for in servers these days?

There are a million configurations of servers, for the millions of possible applications thereof. Even a single game likely requires a multitude of distinct servers (web servers, database servers, compute servers, cache servers, etc.) all with their own hardware/software requirements.

In other words, you need to ask a much more specific question.

In no particular order: Low power consumption, high capacity, low capital cost, high reliability, wide compatibility.