TeachersNotebook.com. The reason I chose this website is Teacher's Notebook does everything for me! They pick the random winners and then email them with a link to download the product. It couldn't be easier! I love the options they offer as well. I can pick the amount of winners, the length of the giveaway, and the products to give away. When the contest is over, I can also send out an email to the people who entered thanking them for their participation and offering the product at a discount (which can be ANY amount...so watch for 50% off deals if you enter!). Math is going to be my personal focus for improvement this year, so watch for those products specifically to be highlighted int he giveaways!
If you have any product you would like to be considered for a giveaway, write it in the comments below. If it is in my TPT store, I can easily add it and make it a giveaway.