What @blue said. I’ve talked about this before in a old post when shadowless 9 was way less than a unlimited 10. To sum things up in the long run there is way less print runs of shadowless over unlimited and theoretically unlimited will overtack shadowless in psa count when comparing the 2. Right now though get the one you want most and just check the count every now and then if you start to notice a change that could tip the value of a shadowless 9 becoming way more valuable then get one and sell the 10 unlimited or better yet keep both if you can afford it later on 
. You really can’t go wrong with either one right now.
Edit: here is the link to the post I made a while back Here . Hope it helps you.