Many experts suggest that you shouldn’t switch companies when you have an open claim.
If you want the claim to be resolved to your satisfaction, it's probably going to be less confusing for everyone if you wait until you've received your compensation or it's been determined that you won't be getting any.
Another important reason to wait is that your new insurer isn't going to know what to charge you if you have an open claim. After all, it won't know if this accident or whatever the claim is was something that was your fault or somebody else's. You could wind up with a higher premium with the new insurer than if you had waited until your open claim was closed.