The Raspberry Pi is a very popular choice for a magic mirror project. The Pi is an extremely cheap yet powerful mini computer that can be hooked up to almost any display. It is lightweight, consumes little power and has a strong community and guides that can help you set it up.
There are several types of Raspberry Pis available, differing in computing power and connectivity options.
You can check install MagicMirror software on it very easily with our 5 minute guide