Guild quests, though routine do have a chance to offer some value materials in your early game progression in the forms of stat promotion scrolls. Typically these will be of the ATK variety but anything helps in the end to increase the bonuses offered by those properties. By hitting S rank guild quests you can then take part in a special short dungeon to allow you to receive some bonus materials that will help you along the way as well. For those that assist you, they too will receive rewards

While doing your Guild Quests, it wouldn't be a bad idea to continue monsters for a bit and go ahead and knock out your Auto Combat dailies as well. It shouldn't take you too long depending on the class.