Color-transparency-slides used to be a professional's favorite;
slides can be relatively-easily sorted, projected, or enlarged/printed.
You can send slides to a film-processor
(like via Walgreens, Walmart,...)
and request enlargements/prints.
Or you can scan them (via HP, Nikon, or Polaroid, ... color-transparency-slide-scanner)
into your-compter, and print them on your color-printer
or send them to a digital-film-printer (like via Walgreens, Walmart, ...)