If you are happy with iOS 12, I would just stick with it. If there is something on iOS 13 that you want or need, then it is probably okay to upgrade to it.
Most of the bugs in iOS 13 on my SE seemed to have been fixed, but not all of them. There also seems to be a slight lag sometimes.
Battery life is probably similar, except I recently got an AW, and the battery life on my SE has been horrible since the purchase of an AW. I am unsure if this is an iOS 13 issue, or just having an AW issue.