[racket] New and lost

Hi all, I have some questions about racket clips and scheme .
Took some time to get into this funcinal programming but I have no idea ,
the fact is that I would like to learn.
But I have a fairly large with different implementations of Lisp mess .
What is the "best" to learn ?
Much racket used? , To be used?
LISP is worth learning ?
Sorry if I ask some silly but as I say I'm lost on this topic .
I appreciate your responses .
Thank You
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