Back then cordless tools have a weaker power output and would require frequent recharging to get through heavy duty  jobs. But these day cordless tools have more power, battery life is improving far than before, and the size of the batteries are getting smaller and also lighter.

the introduction of a lithium battery contribute the biggest improvement for cordless tools. The new lithium batteries will run a tool at full power until the charge is depleted, and it is also allow tools to have a higher voltage and more power while still consider the same as the corded ones.

Now that the difference between corded and cordless tools is less and less visible, the price maybe the next factor on choosing the right tool. the lighter and more powerful cordless tools are more expensive.

The next question is how much tool do you need and where are you going to use it? If you are using your power tool for small projects around the house that you may need more mobility, a less powerful cordless tool might be better for you. If power is your main issue, and you are doing larger projects, and will be less mobile with your tools, the corded tool is probably the one you want to choose. the best idea maybe a combination of corded and cordless tools.