What is the best chocolate to use for this fillimg. Thanks

Well, this may not be much help, but I find that any "good" chocolate in whatever flavor you prefer: white, milk, or dark, makes nice ganache.

I often shop price, so it may depend on what's good, but cheap, and also available in my area. I've used Callebaut, Peters, and Ghirardelli, most often. I like the results from all three.

Rae

All good choices listed above. I have even used Dove Dark chocolate.