You first need to decide whose "bars" you like better, or can get cheaper. Both Yakima and Thule make a quality set up.
You will then need to choose whose "rack" you like better. I have & like the Yakima Big Powderhound for times when we load up the wagon and have 4 boards on top. Only drawback here is that it is tough to get 2 decks with Flow bindings upside down on the rack. Limited clearance to the vehicle roof.
I also have and like the Thule 575 Snowboard Carrier. It is restricted in that it will only carry 2 boards, but it is a much smaller setup, very quick to use. Nice if it is just you or you and a friend. No clearance issues here.
Racks and Bars are interchangeable, so don't be afraid to mix and match. I believe both of the above racks come with locks and will serve you well. Decide what will work best for you and find it at the best price as recommended above.