The answer to your question is going to depend on many things such as which communities are available in your area, what are they like and so on. Therefore it cannot be answered categorically. It only be answered by you. It can be answered by going in person to the buddhist centers in your area, meeting the teachers and people there, listening to what they teach (and comparing it to the suttas) and practicing with them for a bit (and noticing if it leads to peace and letting go). Then you will be in a position to know which sangha is the right fit.
Besides that I would say that all Buddhists should learn a bit about all the main Buddhist traditions (Theravada, Indo Tibetan Buddhism and East Asian Buddhism) so they have a basic foundation on where these communities are coming from. This will allow you to see how they have preserved but also adapted the Buddhasdharma and how they are all unique and valuable traditions. It will also help you to notice when a group is way off the mark. I would also recommend all buddhist seekers to study a bit of the anti cult literature, so they have a basic skill set to identify harmful cultic behavior.
It is my own personal opinion that all these three main traditions are legitimate and one can find authentic dharma in all of them. Even if they are not reading the EBTs, one will find true Buddhadharma in all three. I also don’t think any one of them is particularly more authentic, each one contains innovations and post-early buddhist developments (some more than others of course). The best thing to do is to check out the groups close to you and see where you best fit in.