For short cooks of one to two hours for one or two servings, it's a grab out of the zipper freezer bag box with immersion. For long cooks and larger quantities, vacuum sealed bags only.
Lately I've been doing more vacuum sealed bags as I'm following the recommendations in a recent blog post and other community posts of buying in quantity, vacuum sealing and freezing most of the food for later.
With marinades that's poured out before cooking, when using vacuum sealed bags, just add a little extra length when creating the bag from a roll. Cut the bag right at the seam, pour out, reseal with the extra length.