It's the great question of the craft: copper or stainless steel? Here's the honest comparison.
This is the whole ballgame: flavor. During fermentation, yeast throws off sulfur compounds that taste foul — cabbage, rotten egg, struck match. Copper actively, chemically removes them, dropping them out as harmless copper sulfate as the vapor rises. Stainless steel is inert; it lets the sulfur ride along into your glass. Copper also conducts heat beautifully and evenly, reducing scorched, off-flavored runs. If flavor matters — and in distilling it's everything — copper wins before the argument starts.
For making spirits you intend to drink, copper is the superior tool. Notice the clever path the professionals walk: many large operations use a stainless boiler with copper in the column and condenser — steel's toughness where the wash sits, copper's flavor-cleaning where the vapor travels. As long as copper lives in the vapor path, you reap the benefit.
Cheap is expensive when you buy twice. A well-built copper still, cleaned and cared for, will serve your children.