Rafflecopter is a very cool easy-to-use tool that enables users to enter contests by verifying certain activities and behaviors. It gives companies good exposure, encouraging participation through visits, follows, Likes, and other activities. It has a very low barrier to entry as an end user.

it is a easy way and it has even free version , but basic version will be good ( my personal opinion ) .It even handles a huge number of contestants . So I can say it as best .

Very user friendly and everything is done for you!