ME!! I love the 25 for several reasons. In fact, I just got my first 30 so I can really compare the two now, having only had 2 25s before...
1. keeps it shape better, looks more structured
2. can go from day to night, informal to more formal or dressier
3. actually holds everything I need, including either a change of shoes or a hat/scarf/ gloves set, surprisingly...
4. doesn't bump into people and things as much as the 30
5. not half as heavy as the 30
6. not as bulky as the 30, even when stuffed full
I do love my 30, but it is pretty bulky and has taken some getting used to. It's not good for parties or bars like my 25; with my 25 I could conceivably hold a drink in one hand and raise my arm with the speedy on it to shake hands without looking/ feeling awkward... can't do this with the 30!
The 30 HAS come in handy for me when stuffing a lot of things in, and I like the oversized look (I'm 5'6") but I think if I get an Azur speedy I might get a 25 because I'm scared of all the bumping around my 30 gets.