Managing Form Submissions in Database

I’m working on a project for a client to create a micro site for their giveaways. I’ve created a custom post type for the giveaways, and each giveaway uses the same universal form to capture basic information. I’m searching for the most optimal way of dynamically storing each submission associated with each giveaway.

The two options I’ve been exploring are dynamic custom meta boxes, or creating a new db table and storing/associating submissions using the post ID.

Any guidance on this would be greatly appreciated.