What is your
size? We really have no way to answer your question without knowing your size! This type of lingerie is extremely form fitting, though. It's extremely stretchy, much like stockings (or body stockings if you've ever worn one). So it will likely stretch to fit many sizes, but you wouldn't want to get a size so large or so small that it's uncomfortable.
There's also a size chart. Have you seen it? I am a size 0, and I always order the "one size fits most" with perfect fits almost every single time. From what I've learned from my own experience is if you're over a size 5, you may not find the "one size" to be the best fitting, but it can vary, especially with this type of garment that will stretch to accommodate so many sizes. Check the size chart, give us a little more about your own size. Then, you'd probably be able to get a better idea.