If you're having surgery and will bleed a lot the first day, buy black because the blood will stain and it won't be white/white when you wash it.

White is very sheer but breathable.  I wish it had a zipper for easier to put on and take off.  The is a hole in front and rear for the poopers but I recommend you take the whole suit off if you plan on number 2.

Size, I'm a large and border line X-large t-shirt guy. I bought a Large suit and it works well.