In my opinion, both are important, and their significance depends on each person's playing style. For me, prioritizing account management is crucial, especially since my playing style leans towards safety first. Typically, my winning percentage isn't high, just a bit over 50%, but compensating for this, I manage the position size uniformly. Whether I win or lose, I adhere to a specific betting ratio, not altering it just because a particular trade seems to have a high probability of success. This way, I can consistently generate profits.

You might have a method that yields a higher winning percentage, but without effective control over your account and trade size, you could end up making minimal gains when you win, yet significant losses when you face defeat. I've seen this scenario play out frequently. The best approach is to strike a balance between both aspects, but for me, mastering the control of my account is already a success.