Before I bought my own pfd I had trouble with most all borrowed pfd's riding up and strangling me, while my dh was fine even though he's only a tad taller than me.

I realized this was due to a combination of:
- I have a fairly short back,
- the high seat back on my own kayak and some borrowed ones,
- sitting slightly too "deep" in kayaks a bit too big for me
- most pfd's are made for men

So when I went to buy my own I concentrated on finding one that was very short and high in back. Tried several fancy and expensive ones, but they tended to make me feel flattened like a taco when I tightened them enough, so I finally ended up with a very small and lowprofile, almost junior-size vest. Even that one will rub my seat back a little if I slouch. At some point I intend to buy a kayak where I feel less like I'm sitting in the bottom of a bucket.