I’m 5ft 11″ and had a medium Soul but it ended up being too large for what I wanted. At this height you can actually get away with a small if you know why you want a small. It really depends on how you want it to feel.
Medium if you want the bike to feel more like a ragger; easier to balance front to back so it’s easier to jump and weight the front through the corners. You’ll be going faster downhill and through corners but you’ll feel less like an XC racer on the climbs.
Large if you want the bike to feel like an XC bike – more stretched out so better going up but less able to balance the bike and get your weight in the right place going down. It will be potentially more comfortable for all day rides.
Small if what you want is a play bike for two hour sessions down the woods.
If you tend to drop your saddle on the descents then without question you don’t want the large!