You will need to consider each one separately as to it's value for you. Just because a site is here, it does not necessarily mean it is appropriate for you, now.
What you are led to and what you decide will depend primarily on YOUR receptiveness, openness of heart, and true intention(s). Following that, it will also depend upon the attainment, clarity, intention, life (aliveness), and completeness of the present situation of those you actually reach. These things do change. What may have been vibrant and strong at one time can be degraded or crystallized at another.
This is especially true after the death of the person who brought the teaching through originally. In other cases it can remain alive and grow. In the case of a group which has multiple centers, so called teachers, and meetings run by different people, there will usually be a great variation in the realness and validity of that work. Please remember that you always get in accordance with a combination of your true intentions, needs and potentials at the time.
If you have not read an 8 part writing called In the way, A Primer on Teaching and Learning, it would be good to do so before actually physically contacting people in these groups.
If you are seriously seeking a real teaching please feel free to send an E-mail to me. Please describe what you are seeking and why. Also, please indicate the area of the country you are in. You will get a response - perhaps with more questions. Out of that may come a suggestion for one or more places for you to contact. While there are thousands of organizations, etc.; one will get in response to the sincerity of the search. You may also use the internet to do some searches for the type of "teaching" you are drawn to. You should, if you pay some attention and use some common sense, to be able to determine through looking at their information, web site, etc., whether it has some of the characteristics of a real active transmission. If you have not done so already, you would be well to read on this site, the series of writings on Orders and Organizations, as well as the material required for attending classes in Mentone. These are found on orders-orgs-intro.html and classes.html.