Choosing the right hardware for the job is always a critical first step in computing. A lot of people tend to overshoot hardware by buying the shiniest new device. This can be a lot of fun, but "newer" and "faster" do not always mean "better". First, living on the bleeding-edge of technology can mean that systems may not be fully supported by software you're trying to use, which can lead to instability. Additionally, the fastest hardware is typically not the most efficient. Instead, it's better to choose hardware specifically for the software you intend to run. This should be well-tested and reliable hardware that doesn't draw unnecessary power, and should be perfectly suited to run the desired software without much overhead. A little growing room is okay, just don't go overboard. A device that is on 24/7 will impact your power bill more than you think, so it's important to consider efficiency.
I have a habit of repurposing old hardware for new tasks, breathing new life into them and keeping them out of the e-waste pile. I've found that most old devices can be made useful again just by installing an SSD to improve disk I/O. This is usually accompanied by some distribution of Linux, which is generally a lighter-weight alternative to the Windows installation that originally ships with most hardware. Along with my slew of repurposed devices I also use a Dell PowerEdge Server, several Raspberry Pis, and two custom-built PCs (my main desktop and NAS). Below is a list of my most-used hardware: