K__A:  
Yeah, it seems like a case… but in cases like this, about 4-6 discs can be placed into it

It’s all good

Depends on how soon. S1 box won’t be out until December.
 
Friendship Express and Royal Pony Wedding both have great S1 and S2 episodes. Also F.E. includes the uncensored version of TLR. I would get those two.
 
Also, we don’t know too much about the S1 set other than some rumors. It looks as if it’s all jammed in a single case, which scares me.

Three separate DVDs = about $30 for 15 episodes, a mix of three seasons
 
Box set = $25 for 26 episodes, but all one season
 
Unless you know your niece really likes some of the season 2 episodes on the separate DVDs, save some money and get season 1.

Season One is a complete package, so I would opt for that instead of the three other 3, which would have only a certain selection of episodes.

26 episodes of ponies! That’s like, a little girl’s dream come true! Sure, you’ll be missing some Season 2 (and possibly 3) stuff, but those box sets can be her birthday presents for the next two years

Buy her Clockwork Orange.

Why not buy them all over the course of a few months?
 
Then again, the DVDs with only a few episodes have Season 1 episodes on them, too. So there would be a bit of redundancy, there.
 
Plus, an entire Season in a single box? 9 hours of pony swag? Plus extras?!
 
I think I’d go for the Season One set. It would a challenge for a three year old to watch that much pony and get tired of it too quickly. My two year old brother only likes watching one episode a day before choosing to go play.

I would download every episode and burn it on to some blank discs.

I’d go with the season 1 set.

wait, adventures in the crystal kingdom is out?  
WHAT?!

Friendship express probably has the most variety but I’d personally opt for the season 1 set.