There are a huge number of appliances you can use to grind meat and fat for sausages and salami. As with a lot of things, if you are serious about quality, purchase a piece of equipment dedicated to the job. That said, a KitchenAid with a grinder attachment fares pretty well, but don’t use it for stuffing - please see Sausage stuffers.
I have used a Kenwood MG510 for the past 8 years and it’s been superb (Kenwood MG510 on Amazon).
When choosing a grinder, make sure you pick one that can supply replacement blades, as they’ll need to be kept sharp to ensure a good texture and to prevent fat smearing and higher heat generation during the grinding.