Question: Best age gap for second kid?

We have a 3yo and are considering trying for another. I keep getting wildly different opinions from people. Some say 2 years apart is ideal, some say wait until 4+, some say it doesn't matter. What's been your experience? Any regrets about the spacing you chose? Currently leaning toward waiting til our oldest is closer to 5 but I honestly have no idea if that's smart or if we're overthinking it.