What ever methodology you use, the key issue is how you use this data in order to create messages. However, many of these groups would have similar needs, such as social needs or safety. Therefore, I would suggest focus groups or, one-on-one interviews to get more quality out of the answers, and quantitative research will give you only statistical values, but qualitative more material for messaging.  

Beside the qualitative methods (in-depth interviews and focus groups), content analysis may help as a starting point. I would try to find out the online platforms each group prefers/uses and analyze the content they read, share and follow. For the entire group message, I would suggest to look for a common ground between the groups either from the interviews’ data or the content analysis to use for constructing the message.  

While Maxdiff analysis would yield important preference information about consumers, converting this information to "best" message is another challenge because by the term "best" message, we probably mean the message that would yield the best possible "results". As already noted by other contributors, focus group or depth interview might be of help. In addition, results (or consumers' desired response) are not only dependent on the message itself, but also on how the symbolization and execution are done to elicit consumers' response in a macro context. Thus, in addition to what has been mentioned in this thread, it could be added that once the most important criteria are identified through MaxDiff and/or other qualitative techniques, a small scale post-hoc experimental design may be necessary with the same message being executed with different sets of symbolization and execution styles. This would probably enhance the actionable value of market research and find the best possible combination of message and execution style.