These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Mizuki, partially because she is seen as kind of bland and her departure to Dream Academy for rather poorly written reasons.
The Dream Academy girls are well accepted among the casual crowd, but in serious circles they are hated.
The fact that two of them use already established brands instead of new ones is also a point of contention.
Otome's whole schtick is seen as either cute or idiotic.
The Angely Sugar and Spicy Ageha brands are becoming this due to their overexposure.
Akari, due to fears of her replacing Ichigo somehow.
Canon Sue: It's very hard to see Ichigo as anything else but this, mainly because in spite of having tons of characters, the anime focuses more on her and her personal triumphs, even against obstacles she really really should not succeed.
On the other hand Ichigo is the central character and Audience Surrogate when it comes to the workings of the show so it makes sense for her to get the most focus. Ichigo also doesn't win everything such as the third spot in Tri-Star but when she does she goes through very intense training even for fairly simple obstacles.
Franchise Original Sin: The first 3 episodes of second season is criticized for reusing the same insert song, which is a rock remix of the second insert song of the first season. This also happens in the first season, albeit that it was the first two songs that get recycled for 3 episodes as well.