MacBook Pro :: Charge It Or Let Battery Drain During Normal Usage?

Is it better, during normal usage, for example at home, where you could either charge your MacBook Pro or let the battery drain until it is used up (5%, ...).

Some people say that letting the battery cycle is the best option, yet other people, including my friend who had lost many many cycles even though he had attempted precautions (Dim screen brightness until one block remained, wireless off, bluetooth off) had said that having your laptop plugged in as muchas possible is the best option, as there would be no cycle change.