I don't operate a business but I have a few enterprise PCs for personal use; HP Z series, G3 Minis, Lenovo Thinkpads, and my Thinkstation. I think what the best performance means to me is the usability of the machine despite not being the latest or fastest model. I'm still using all of these older systems for various tasks, the P520 is my main PC, a Thinkpad E560 is my mobile gaming rig, and I also use my 2014 HP Z230 from time to time. They just work for the things I need them to do.
If I purchased another enterprise PC to update my current one, what I would need it to do better in the next five years is just keep working, as in turn on and perform the same every day. Ideally, if I were to update to another business PC, the only thing I would need it for is simple gaming improvement. An example would be updating to a Lenovo T470 or 480 so I can have a more powerful laptop to play games without purchasing a gaming laptop. Everything eventually becomes obsolete, but there is no need to buy the latest and greatest or the most powerful unless you need it.
In a business environment, I guess that would mean that I would only need to update for better computing, something to make the job easier or improve the workflow. For example, my workplace has wrenches of all sizes, but what would make the work easier is a ratcheting wrench to speed through bolts and such. There is also no reason to buy an expensive wrench set when the best value wrench will do the same job.
I'm not sure if that's the answer you're looking for, however.