Afraid I don't know a thing about WIT or CIT however I have come into fairly frequent contact with graduates from DIT UCD and queens (I attended DIT between 82 and 88).
Basically all of the courses have their pro's and con's. As you will probably have noticed if you're keeping an eye on Archeire there has been a fair bit of concern about the course in Bolton Street expressed recently and from my own experiences there I would tend to think that the situation there has pretty much remained the same from when I graduated in 88.
Bear in mind that much of what has been said is probably on the part of Bolton Street students and graduates and although it all rings true you will probably find the same complaints (if you enquire) are made of all three colleges.
For what it's worth, professionally the three courses seem to produce graduates of much the same calibre and capability. In each case, in the end of the day each colleges graduates have particular weaknesses and strengths. No one college is 'overall' better than the others.
I have found that although the UCD course seems to produce very 'literate' architects in terms of both theory and professional practise that a significant number of their graduates tend towards a 'painting by numbers' view of architecture, in other words they all tend to be stamped from the same mould and you would be hard pressed to find much (initially at least upon graduation) in the way of independent thought from graduates of this course. On the other hand the UCD graduates have an excellent work ethic and are very well thought and in my day always seemed to have the upper hand on DIT graduates in terms of the kind of office that they ended up in (this is worth bearing in mind as your first two years post graduate pretty much mark out the rest of your career.
Bolton Street on the other hand does tend to leave (abandon?) the student to his own devices (some would say too much so) partly as a result or consequence of poor quality of staff and partly as a deliberate method of forcing the student to think for himself, and their graduates are much more individual both in terms of quality and personality. This can be very advantageous if the student has a lot of self confidence and can learn on his own however it requires a lot of individual talent and application to succeed in that type of environment and does seem a somewhat negative in the end of the day. Bolton Street graduates are quite employable and generally shape up well in a professional environment. I would add however that they take more time to come into their own professionally than the from UCD ,perhaps as a result of a lack of self confidence instilled by their educational background.
As to Queens, they always have had a bad press in this part of the world, interestingly enough however, they generaly seem quite happy with their course. When I was in College, Queens students were regarded as somewhat 'flakey' and of fairly poor calibre. A lot of this was based upon the fact that they always lagged badly behind the two southern colleges from the point of view of student design competitions. However I have worked with quite a number of Queens graduates and was very impressed so they're certainly doing something right.
Frankly, all of the Colleges have their advantages and disadvantages. (My own personal opinion is that architectural education in this island lags badly behind that in the UK). However I would say that irrespective of the College attended, the end of day standard is pretty much uniform. If I were asked to grade I would probably, rank UCD graduates as best. Remember that for all that Bolton Street cherry picks 'suitable' students by interview and aptitude tests that it is the UCD students (chosen at random irrespective of aptitude by examination points) who seem to be of the best overall quality. This would seem to say a lot about the teaching regime at UCD, I would guess that if they can achieve this kind of standard with a random sampling of leaving cert graded students then it should definitely be a good course for a student with even a modicum of talent and ability.
Finally, on the basis of Architectural Awards UCD graduates would appear to have been sweeping the boards over the last few years. It might be worth checking this statistically with the RIAI in Merrion Square.
Hope this is of some assistance