It depends on what you are electrolyzing. It it's just water with ions to conduct electricity, stainless steel will only corrode slowly but if it's a chloride solution or something similar you'll want a DSA (Dimensionally Stable Anode) the most common one you'll find is called MMO (mixed metal oxide) which is titanium metal coated with a very stable oxide such as lead dioxide, cobalt oxide, manganese dioxide or the best are ruthenium and iridium oxide because they are very stable and catalytic in the oxidation of chloride to hypochlorite and chlorate. I have sold several ruthenium and iridium oxide anodes here and have plenty left if you want some ($3/ sq inch.) shipping is free to the US.