Id say improve yourself where you can. You can focus myth's at BiS at 1st but at some point you'll have to decide what to get with your coil drops, while keeping accuracy high enough. You can try to hold out for w/e coil drop you want in certain slots but due to rng you may not have any of them before next ilv upgrade release, or you might buy 1side grade myth piece and get that piece next coil. Hope for the best, expect the worst. Also keep in mind that even if the item you want drops and your needing against another tank, there's another rng chance.
Anyways Debby Downer out.