What's the best windows laptop for heavy use and multitasking?

It depends on what games you play, but for a heavy-gaming laptop (light-gaming would be like minecraft and the sims), you will have to spend at least $1000: I recommend you look into the Lenovo Y50 or Y70. Other great options would be the MSI GE60, GE62, or GE70, Asus GL551JM or Asus G750JM. The most expensive one, obviously. I would suggest just getting a gaming laptop. They have more processing power than normal computers as well as the rest of your criteria. They tend to be a lot more expensive thought, but you have to pay for function.
Asus is a great brand for gaming pcs. My fiancé and I both have them. He has an Asus rog I believe and it was about 2000 dollars. He says it works great and he's a heavier gamer than me.

The most expensive one, obviously.

I would suggest just getting a gaming laptop. They have more processing power than normal computers as well as the rest of your criteria. They tend to be a lot more expensive thought, but you have to pay for function.
Asus is a great brand for gaming pcs. My fiancé and I both have them. He has an Asus rog I believe and it was about 2000 dollars. He says it works great and he's a heavier gamer than me.