There are no piercings that every single person is going to find painless. Pain is totally relative, what was painless to me likely won't be painless to you and vice versa.

And really, all standard piercings are generally super easy to get when they're performed well. A quick hard pinch, it's over in a matter of seconds. Base your decision on what you like the most, not what may or may not hurt the least.

But since you asked for suggestions, septum & daith. Septums are generally super quick & easy to heal, and daiths are tucked away in your ear so they tend to be one of the easiest cartilage piercings you can get, as they receive less stress.

If you had your ear lobes done and remember how much that hurt, slight prick (say 1 on pain scale), top of the ear hurts a bit more (3-4) because it has more nerve endings, and can throb for a bit afterwards. Navel, for most, does not hurt at all (1-2), or only very little, like the ear lobes.

The highest concentration of nerve endings, or most painful areas are the nipples and some of your private parts (the highest 9-10). Heard one girl say her LEAST painful was her clit hood. - so these can vary for you, too. The tongue for most is just below the nipples, maybe 7-8. With the least painful the ear lobes everything else is generally in between.

That is such a bad reason for wanting to get a piercing.

belly button doesnt really hurt to get done, but the healing is bad