A Nageki without memories is happier normal Nageki. He never had a family (and therefore never lost them), was never sick, never killed anyone or died, never spent years completely alone and without memories, and doesn't remember any of his friends before Wonderland. He's happy because, as far as he knows, there is nothing to be sad about. He has food, shelter, good friends, and all the books he could ever ask for. He's still loyal to the friends he has, although they aren't quite as important to him as they are normally. This Nageki will actually move from the library and go out of his way to spend time with those he considers friends (Mikan, Kaneki, Max and possibly some others). If any of them ask Nageki to do something, he'll pretty much always go along with it. He still doesn't go out of his way to make new friends, but he really enjoys spending time with the ones he has.

His Mirror is also much nicer. He still watches over Nageki, but he started writing notes to Nageki on the mirror or to other people. The Mirror annoys Nageki by mothering him and passerby might sometimes find notes telling them to remind Nageki to eat or something like that. Neither of them remember that Nageki is a ghost and act as though Nageki is a normal bird.

The inconsistencies are easy for Nageki to gloss over because all this is normal. He can't remember having previously lost his memories, so they aren't something he worries about. He just cares about the present.