What is the most valuable business resource today? Is it people? Human resources ARE an entire business unto itself, so you could argue that this is the most important resource. If not, then it must be at least near the top of the list.
Another area might be all the small business equipment involved in running a business. You can’t do business without having the tools to do the job right.
However, I would say that the number one business resource today is ideas. A single idea can turn into the next multi-million dollar corporation for anyone brave enough to follow it through to completion.