Can anyone tell me the stock string size and brand that comes on the JTV89? or what is the best string brand for use on electric? I've been using Elixir for acoustic for a long time and not sure if that's the best for electric.
D'Addario 10's come stock.
As far as the "best" string brand, you have to experiment and find what sounds and feels right for you. I've found Elixirs to be a bit bright for Variax, but your opinion may be different.