Everyone's body is different so it's hard to say what's going to heal the fasted, which is the least painful etc. because pain thresholds, healing processes vary from person to person. However based on personal experience, getting my nose pierced was the least painful for me, followed by my lip, I have a pretty high pain tolerance I would say so they were probably both like a 3/10 and they both healed pretty quickly. I had my belly pierced at 18 and it rejected, I had it for about a year before finally deciding I should take it out and it ended up leaving a scar, but again, this is my body so it may not be the case for you. My belly was my first piercing so from what I recall it was about a 4-5/10 pain-wise. I've never had a simple cartilage piercing before but I have an industrial which is the bar that goes across the cartilage through one side to the other and the actual needle is thicker because the size of the piercing is thicker, so that hurt a fair amount for me, I would say like a 7/10 and it took the longest to heal apart from the belly which never did. I think it took almost the entire year after I got it for it to properly heal, before that sleeping on it could be quite painful, too much pressure and it would start bleeding and it was almost always crusty. However, as weird as it may sound I don't regret it, my industrial is one of my favourite piercings as well as my nose. Since then I've had my septum pierced and that was the least painful piercing experience I've had to be honest I would say it was a 2/10 but septums aren't for everyone. At the end of the day you should get the piercing you want the most, rather than avoid the ones you anticipate to be the most painful, because and given you go to a professional who knows what they're doing, it's basically a second of pain before it's all over, and a second of pain for a piercing you really want seems worth it to me.