I bought the 6-quart Presto since I cook large amount to freeze, but I would recommend the 4-quart, it's safer & faster to build up the pressure.  For the 6-quart stainless steel Presto:  Pros  1) enough for 6 servings.  Cons:  1) smaller bottom & takes longer to build up to pressure  2)  Takes longer to heat, due to large size  3) More dangerous, it's heavier, plus doesn't fit into sink without tilting over, releasing hot steam from the trivet (pressure regulator knob).