There isn’t one universally “best” medium—different images suit different surfaces. Based on the answers, canvas tends to give a softer look, so it may be less suitable if you want maximum sharpness and punch. Acrylic, aluminum, and glossy photographic papers can all look vibrant, but they may also be more reflective under gallery lighting.

A strong practical option is to print on quality photo paper and mount it to a rigid exhibition board. This can give excellent results, may be more economical than acrylic or metal, and keeps you closer to a medium you already know. For gallery use, luster or matte paper is often recommended over glossy because it reduces distracting reflections from ceiling lights and spotlights.

If presentation quality matters, use proper exhibition mount board rather than basic foam board.

The best advice is to test: make small sample prints of the same image on the media you’re considering and view them under similar lighting. That will tell you far more than specifications alone, especially since your exhibition includes a mix of subjects and both color and black-and-white work.