We should definitely be in group 3.
To completely ignore personal experience is to ignore what teaching is. It is hard to be research in education. How, for example, does one objectively evaluate how different methods work? So, if we are interested in taking about how concretely to improve teaching, then we have to rely on personal experience.
To completely rely on personal experience would be bad because we then turn into a discussion. Experiences will vary. Many teachers have limited experience in that they have taught only certain types of classes. Some teach high school and others direct graduate students in college. But both groups have to deal with some of the same issues (e.g. how do you motivate students?). I think a good answer is honest about the level of experience of the person providing the answer.
I think the best middle ground is to require some level of "objective information" in the answer. There are many education/psychology journals out there and I think that whenever possible we should encourage people to support their personal experience with research or other objective information. This might even take the form of pointing out that your experience matches that of this other person who wrote about it somewhere.
Part of the reason for requiring a bit of objective information is that it makes the person stop and evaluate their own beliefs. Are my experiences supported by any facts? Just as with an argumentative essay, the argument becomes much more forceful if you can cite a few references.
Again, this is difficult and if you look at the few answers that I have given, I have filed at this. I still would hold to the above point because I think it will elevate the quality of the site and increase the likelihood of its survival.