With those two as choices, I would go with the cream. I did a BOM a few years ago and waited until I got all the blocks to figure out the background fabric. I actually based it on the boarder fabric that I used. I ended up choosing a light teal color that worked with all the blocks and there was a variety of colors in the blocks, like you are doing. What I would suggest is to think about how you plan on finishing the top and if you are adding any boarders. If so, try a light color from the boarder to tie everything together. The background fabric choice at this point might surprise you, like it did me. Best of luck and can not wait to see it finished.