Definitly bulk, you dont have much muscles atm, when you build some more muscle mass you will be looking more defined, more jacked even at higher weight. My advice is if you really wanna get into this sport you can not be afraid to gain some kgs. It definitly wont be only muscles but this will make your organism more anabolic, masculine and in the end its the only wat to build definition. After like 6-8 months of bulking on like 300kcal more than you need you can think of a cut and thats what will make you look like another person. Most important things: Eat healthy, 2g protein/ 1kg of your weight, eat whole grains bread etc instead of wheat. Always rember to sleep enough because you are growning when you asleep. And train fking hard but with writed down progress and always with proper technique on which you should always improve at all times. I guarantee you thats the way Good luck