Should I learn takedowns or pull guard?

Takedowns.

Pulling guard means sitting down on purpose and inviting somebody into your legs. In a tournament, with rules and mats and a referee, it is a legitimate opening and good people do it. Everywhere else it is a habit I would be careful with.

Whoever decides where the fight happens is winning it. If you can shoot a double, finish a single, or trip somebody off a body lock, then the floor is your choice. If sitting down is all you know, you have handed that choice to a stranger, and on concrete with somebody on top of you that is a bad trade.

Takedowns are also the hardest thing in grappling to learn, which is the other reason to start now instead of later. Stance, level change, timing, and the willingness to get tired. High-school wrestlers walk in with all of it already, which is why they pick no-gi up so fast.

None of this makes guard optional. You will spend plenty of time on your back because everybody does. Learn both. Take them down, and know exactly what you are doing in the two seconds after you both hit the floor.

Before the takedown there is the grip fight, and that is the part almost everybody skips. Hands, wrists, collar ties, the small war over who gets an underhook first. Same range as the clinch in striking, and whoever wins it decides where the next ten seconds happen. That is also why this part matters so much outside a gym: nobody in a parking lot stands politely at range, they close and they grab. See how much of jiu-jitsu is useful for self-defense.

One warning. Takedowns land people, and landing is a skill of its own. Breakfalls come first, on mats, with somebody who knows how to drop you safely. If your back, neck or knees have a history, tell me before the first rep, and see a doctor about anything that actually hurts rather than aches. Ask me how I want to build it when you message me.