The 316 should be superior as it has about twice the yield strength of the 304. However, it is also twice the price. I’ll play it safe and get the 316. It’s either $72 for two 8ft pieces of 304 or $147 for two 8ft pieces of 316 shipped from onlinemetals.com for me.
Edit: I forgot to apply the coupon code earlier. It was only $113 shipped.