In an interview I was trying to make a statement that school A I had
attended focused more on skills applicable to the job, than school B
that I am currently attending.
In reading the above line I would wonder, "Why are you going to school B?" If the other school focused on the skills for the job then what is going on here? This to my mind is where you may be shooting yourself in the foot as one could be left going, "So why are you doing what you are doing and how does this fit with this position you want to hold?" There is the potential to come off as someone that isn't going to stay in the job that long which could be a turn off in some cases.
Notice that you don't state what you said but rather a summary of it.
What would the appropriate response have been?
Consider what point were you trying to make to say that, "This school I attended before prepared me well for this job and I'm now going to this school," that I'm not sure I see where that is going. You don't really state this anywhere what point were you trying to make. What was the interviewer supposed to know after the statement that makes you look like a better candidate for the position?
In interviews should one try to be as neutral as possible and never
say "this is better than the other" or "x does more of something than
No because this could be worse actually. There are times where you may be asked why you chose to use technology X and this is where the key point is how well can you support your position. Someone may look at my resume and ask, "Why did you use C# instead of VB.Net when getting into ASP.Net?" which can be answered in a way that isn't bad mouthing VB.Net. "The programmers were versed in C-like syntax and decided to use what they believed would have less of a learning curve," would likely be my answer which is honest about why it was chosen. There is something to be said for how you explain why you have the position you have as chances are you will have to make design choices where comparing things is done and explaining why a choice is right is a necessary skill. "Because I said so!" doesn't often work well with other developers in my experience.