The Silver Puppy and SilverGen machines are really good ones and the Silver Edge also has highly regarded machines. Those may have the best combination of features for the money of the home machine, and they make good home products.
My choice, and what I have, of the best actual product for the money, has fewer features but produces small particle silver that is about 70% ionic and about 30% true colloidal silver (which is more true colloidal silver than any home generator I am aware of) is the Utopia Silver Silver Bullet:
Which you can get with TDS-1 testor and a timer for about $100 when you use the CureZone discount code of LR001
Another benefit of ordering that silver maker is that you get a life time half-price offer (buy one, get one free, that is) on their Advanced Colloidal Silver - which is many, many times more powerful than any home produced product and a good idea to have around in the event of a really tough bug or condition.