Think I'm liking one-time events that increase stats a bit.
I recall Golden Sun had quite a few different items that permanently increased a stat, one item per stat. They were surprisingly mundane, though, like bread increasing attack, mint increasing speed, and nuts increasing defense. Can't recall what the others were at the moment. They were mostly all found just by checking pots, but a very small handful were quest rewards or in plain sight. As noted, there were really not too many, and unless the drop rate was ultra-low, I never encountered an enemy that dropped those items.
Reason I brought this up in the first place was because I found a set of free stock art that I thought we could use, but they're all potion colors. Fit the art style much better than the last set of stock I asked about. Found
here for your consideration.
...although I'm also veering more towards mundane items and events. Those sound a lot more fun!