I also liked the episode Future Imperfect, where that alien child creates a 'future' which involves Riker waking up "16 yrs in the future".
Me too. I thought it was sweet how Riker said at the end,
"I'll always think of you as Jean-Luc". I actually liked the kid's true form, because it looked more convincingly alien to me than all the races on Star Trek that are clearly just humans with weird foreheads.
And even though they said
"she's turning into a woman", Miri (from the episode of the same name) seemed very child-like to me and I liked her. The kids in her episode were way more watchable than the horribly lame villains of
"And the Children Will Lead" (I think everything about that episode sucks).
The kids in
"Rascals" were great. I loved when kid Picard got pissed at the idiot computer and when he threw a fit so he could talk to Riker. Kid Guinan teasing kid Ro was cute too.
Maybe my favourite children on TNG were the kids stuck in the elevator with Picard in
"Disaster". It was fun to see Picard thrown into that uncomfortable situation since he generally didn't like children, and really funny (because it was so in character) how he turned them into an efficient survival unit of a team. The bit at the end where he says,
"Number One" and both Riker and the little girl from the turbolift think he's talking to them (because he appointed her as his Number One when they were trapped) was adorable.