- sales are mixed bad, discounts used to be a lot higher on standalone but now its mostly the same for steam and standalone- not a factor while choosing steam/standalone
- steam uses steam wallet which is really helpful in saving some money if you are engaged in some steam market activity like selling items on steam market etc (i fund this way most of my purchases on steam, without need to use my "real" money)
- much higher download speeds on steam
- automatic updates on steam
- refunds on steam
- negative reviews on steam, which are pure comedy gold (mostly, like the one saying dcs is hard)
few points from steam user ;>
edit: Steam uses regional currencies which sometimes lets you get a better deal or save on exchange (depending or your payment option), not to mention more payment options over all