I beat Persona 4! (
@Bolderousness since you requested it)
The final boss was tough - someone told me about an overpowered Persona (a level 75 Tower fusion whose name starts with Yoshi, but I'm not typing out the full name in case it becomes a case of censor dodging) that gets a really powerful skill at level 83. It took that, accessories that half a character's SP use for both Naoto and Yukiko, and a TON of level grinding, but I eventually beat the final boss.
The only other Persona game that I've played is Persona 5. Compared to that, I felt like Persona 4 was tougher (I was low on SP until Rise got to level 77, and refilling your SP is incredibly expensive for most of the game), though I only won the final battle of Persona 5 due to luck (Futaba got an ability that has a chance of activating if someone is going to die, which saved my party from being killed by the boss's final attack).
However, I felt like the characters (or at least the party members and the Dojimas) were more memorable. I didn't find the supporting cast as interesting, so I was able to focus most of my attention on those characters (and the fox and Margaret, since the Fox has tangible benefits and Margaret's gets me some powerful Personas) and I was able to make a deeper connection with them. By contrast, I sometimes forget about Haru, and she's one of the party members in Persona 5. (whatever social stat is required for her storyline is one that was nowhere near high enough during my playthrough)
I'm looking forward to playing Persona 4 Arena Ultimax, though I've been told that the game contains major spoilers for Persona 3, so I should probably play that first. I'll wait a bit before jumping in, though - I don't want to feel burned out on the series. (kind of weird that I've been going 5 - 4 - 3 as far as Persona games are concerned; I might look into Persona 2, though 1 is probably going to be too outdated/difficult for me)