No.  In this case bigger is not better.  Air conditioners work to both cool your house and remove humidity.  A unit that is too large for your home will cool down quickly but will shut off before it has a chance to remove the humidity reducing the comfort level of your home.  Too much moisture in the air can also lead to mold and mildew. If your furnace is oversized, it will heat up your house very quickly but it will used more fuel and lead to greater temperature swings.