In a recommend what you use way:
Epson Perfection V600 PHOTO.
It has various trays to suit film negatives and slides of various dimensions and software to sort out colour B&W etc. I’m not going to say it’s fast but the results are really impressive when shown on a TV. The biggest problem is dust and grot on the slides, if anyone has suggestions on how to get sticky dust off slides without damage I’m all ears.
Edit: the digital clean-ups do or don’t work depending on what the subject is. I’m not sure I’d want to spec it on every slide if done commercially.