I’ve never used a slate before. I like the box call and have a push button still from when my kids where little and let them learn to call with it. Primos has a good selection of them. I used a diaphragm call mostly.
If you haven’t already, check out YouTube and the “How to” videos on box and push button calls.
Box calls are the easiest IMHO, but every one sounds different, just like no two turkey sound the same, so don’t listen to the guy in the store that is trying to tell you his calls mimic turkey more closely.
I learned more by listening to the hen when I was hunting. I would mimic the same call they were doing and than watching YouTube and what other people would tell me. Nature is the best teacher to have.