The fatter you are, the easier it is to cut fat. The leaner you are, the easier it is to accrue lean mass in calorie surplus without excessive fat gain. It is far more advisable to wholly dedicate to one or the other. You can succeed at one or fail at both. Honestly though, its purely your personal preference. If you're over 15% BF I would cut down before attempting to add lean mass. This is only my personal choice.