This is a good look at the stance I use on all my SUPs in surf or flatwater.
The modified surf stance is what I find most stable and comfortable in all conditions because it offers frontto back stability as well as side to side. It also requires the least amount of "correction" when I get bobbled by backwash or chop. Many prefer the "wide parallel stance" but I find this works best for me. Please let me know what you think in the comments!