I would go with the SSD for the operating system and some programs that are essential or going to get a lot of use. And the HDD for everything else. So SSD and HDD combination. I have a 500 GB SSD, 3 TB HDD, and an external 320 GB HDD. I use my SSD for the operating system and programs while I use the HDDs for recording gameplay for my YouTube channel. This system works really well for my needs, so if your needs are similar then you would benefit from it too.