Frankly, if you are shopping for the best cordless drill for your biggest and best household projects and it will be the first power drill in your home tool kit, you should not start with a cordless drill. You will get a lot more power from a much smaller, lighter-weight corded model than you ever will get from a cordless. If you survey the pros' tool boxes, looking at what they have and which tools show greatest signs of wear, you will see their 5/8's inch corded power drills show all the signs of tough love and everyday use. If you ask, the pros will say, "It is all about the power-to-weight ratio"; when you hold a corded drill in your left hand and a cordless in your right, you will understand how to calculate the ratio.
The pros bring out the cordless drills only for specialized work where they do not enjoy easy access to power.
If you already own a satisfactory corded drill and still seek a cordless drill for specialized work or a job where not even a generator can assure you have the power and reach you need, invest in the very best drill you can afford. You must understand, especially with cordless tools, you get what you pay for; words like "economy" and "bargain" translate to cheap and unreliable. The big name brands still deliver the greatest value and reliability, and you ought to plan and invest as though this is the one and only cordless model you ever will own. Three well-respected brands perform equally well, so that your needs and today's market conditions probably will determine your choice. Look long and hard at Milwaukee, Bosch, and Porter Cable 18 volt lithium ion drills.
Match your tool to your toughest project.
No indoor project ever really warrants a drill with no cord; but several of your biggest and best outdoor projects easily will give you an excuse-or more properly an "occasion" -to buy the cordless drill of your dreams. If you plan to build a redwood deck, anchoring your 2×6 planks to your supports with Teflon-coated deck screws, a good cordless drill will make the work considerably easier and the results considerably more professional. The same rules of thumb apply to your dog's new two-story house, and your custom gazebo, and eventually to the guest house or studio you know you need and want.
As you search for the name-brand drill that delivers maximum power and durability, carefully consider the drill's weight. You will carry that tool around all day for several days, and the combined challenge of holding it steady and supporting its weight will take its toll. For several hours after you roll-up your gear and quit for the night, you will feel "the phantom drill" in your hand and forearm. Read the product specifications with a fine eye for details, because several manufacturers wisely list their drills' weight without the batteries. Naturally, you want to find the best cordless drill that has the most power with the fewest pounds.